Of course you could always make up an explanation, but there is actually a need for the story itself to do the confirmation and not an external source. You see, even if you provide hints, there is still uncertainty. After all, hints aren't the only thing the author can provide, they can also give Red Herrings or use techniques like Unreliable Narrator where misguiding the readers is the goal. Your readers can't be entirely certain until the story confirms it is so.
Also, you have called it foreshadowing, yes? The nature of foreshadow is to be imperceptible. In fact, lots of authors do tricks to make the readers gloss over them. They are at their most effective when their significance only comes to the readers in hindsight. This is why I said that foreshadowing isn't used for the purpose you are using it.
And the reader did make things up themselves. The thing they made up?: Your protagonist is stupid. See the problem when you let your readers have to much leeway in make things up? They might make up things that you don't like or don't intend. You have to make it clear, in this case, or your readers might go into strange directions.
Look, I get that you are trying to help but you're really not. Without knowing the story in question, you're just guessing blindly here and that's not going to work. Half of what you're saying isn't even applicable to my story. To be able to really try and give advice, you would need to either have read the story or need a much more detailed explanation which I didn't give because I was really just intending to share a short anecdote of "this kinda thing happened to me".
I am not looking for help because it's not a problem for me. The part in question makes sense in the story and I have enough checks in place for it to not be troubling to pretty much all readers except for maybe one or two. And I'm not worried about one or two people being confused by something because there are a multitude of reasons as to why that might be the case: They might be prone to overthinking (which is actually lovely because those people come up with the wildest shit which I love seeing!), maybe they skipped some stuff (readers do and if they don't get stuff because of that, that's on them, not me), or perhaps they are part of that group that doesn't actually read the English version I put up but a version in their language that they get out of a machine translation (had a reader like that berate me before for misusing pronouns which is an issue with MTL and not on my part but they were
so sure I didn't know my pronoun game). Looking at the demographic reading online, it could even be that they are just lacking the language skills to get some of the intricacies so some parts of the story might stump them no matter what I do.
So yeah, I'm happy with the story as it is, I don't need advice, and if I needed it, I would make a new thread about it with a much more detailed explanation so that people would be in a position to give that advice in the first place. Thanks for trying anyway but it's really not needed in this case.
Well, if the whole story is available at that moment then yes it is not a plot hole. The reader just haven't go to the part where the explanation is. But with a serial like this? There is no explanation yet. Sure, you might have it in your head, but for the readers, they would not find it no matter how they look, because it is not there. Heck, for a reader, they can't even be sure if the author actually has any explanation for it. That is one difference between a serial and a book.
And sure, you don't need to explain everything especially when it comes to secrets, motivations, backstory, etc. but that is not true to actions (or inaction). If a character do (or not do) something, there has to be an explanation for those. If your character ducked, it is because someone is punching him; if your character is scared, it is because the room is dark; if your character doesn't shift into a child, it's because of distaste or something. If these is no reason why they do (or doesn't do) these things, then things becomes really off. Why is your character ducking? Why is your character afraid? Why is your character failing to use the obvious solution? Their actions (or inaction) is detached from any causality and comes out of nowhere.
Again, it is because they are not reading a book. Sure you could continue reading until you found the explanation… when you read a book (traditionally published, yes?), but for serials, where the chapter is written and published one by one, you can't continue reading and look for the answer, because those chapters (and in turn the explanations) aren't there.
And in the specific complaint in your story, it is more of your character not even considering the obvious, mundane solution. I don't think it would be a problem if your character did consider the solution but end up disposing it (because of some motivation like aversion of something). But to not even think of it?
The thing is that those comments usually come in when at least several volumes
have been posted and the answer is long given, not while I am serializing the specific part they are troubled by. Also, even with a serial they could, like, wait for the explanation to come out instead of just assuming the author doesn't know shit? Alternatively, you can always ask
why instead of making that assumption.
The assumption in question being their first (public) reaction is what I have a problem with. Not getting something (yet) is obviously okay and it's no shame to question the part and wonder why. Like, I also have readers who are like "I wasn't sure about x, is that going to come up later?" or something. It only becomes a problem when (and I've unfortunately had to see that happen as well) a reader doesn't understand something and then starts ... well, trying to shame the author for not doing their job or trying to make factual statements like "This is a plothole" when it's really not because there are several logical explanations readily available to them even if they can't think of the actual one that will be given later on.
I've legit had a reader who made the statement "No effort was put into this story" about a short story I spent hours researching for, two weeks drafting, that I revised and edited several times, poured hours into making the cover, days into translating and again editing it and remaking the cover for the edition in that language. So making a statement like "no effort was put into this" as if that's a fact is kinda rude, doubly so if you have the author right there and could
ask but don't bother doing so but will bother telling them they weren't doing their job. And it's usually this kind of rudeness the readers pointing out "plotholes" display. At the very least, it is in my experience. Could be you have made different ones, that's valid but this is how I've experienced these things and that is the point where it becomes a problem to me. I just want people to think for a moment, then ask, and not outright accuse.