To me this is the single most annoying issue because it severely limits the functionality of the website.
Using chrome on my phone (Moto e4), I can scroll down but not up. If i try to scroll up, instead of scrolling it jumps to the top of the page. (Actually, it acts like it's going to let me scroll at first but only as long as I keep my finger on the screen. As soon as I let go it jumps).
As an example, if a post has a large number of comments on it, and i read down about halfway but then someone puts a comment that refers to another comment that was just a screen or two before but i didn't really pay attention to it, so now I want to go back and read that comment, so i try to scroll up a little and then BAM. I'm back at the top of the post and I have to scroll down again but now I'm not sure just how far down i was. So I just flip the screen to let it scroll down really fast, stop at a random spot and realize that maybe i went a little too far, so now i want to scroll up again. Maybe just a little? But then BAM, I'm back at the top of the post again. ... And repeat.
This also happens, not just in posts but in the stream and also on the People section. So if I'm looking through to see if there's someone i recognize, I scroll down.. it can only go a little bit then it has to buffer to load the next group. There's hundreds of names there but it only shows about thirty or so at a time. Maybe I've been at it a while, it takes A LONG time to get down to the middle. Maybe I'm in about 400 names. That probably took me a good half hour just to get there. So if I accidentally scroll past somebody a little too fast, then try to catch it and back up, well.. BAM.. back at the start.
This is annoying enough to make me stop using the website altogether.
I tried mentioning this once before but based on the response I'm not sure if the problem was really understood or not