Yes, this is almost certainly a technical issue. The way reddit caches things probably isn’t the standard way you’re thinking of, like a short-term cache that expires and refreshes itself. There are multiple layers of “cached” listings and items for almost everything, and a lot of these caches are actually data that’s stored permanently and kept up to date individually.
There are also multiple other places and ways that comments are cached—comment trees are cached (order and nesting of comments on a comments page, for all the different sorting methods), rendered HTML versions of comments are cached, API data is probably cached, and so on.
All of these issues are probably just some combination of all of your posts being difficult to find and access due to the listing limits or certain cached representations of posts not being cleared or updated properly.