IOS app, latest version.
On threads I've posted on, when I've bookmarked the latest post. If I come back to the thread and want to recall what I posted, I scroll up to find my post and it's not there.
Happened several times recently on different threads. Most recently it keeps happening on the November Declutter thread.
I don't know if it means other people can't see my posts either or if it's just me.