This looks very much like a something todo with loading slider interfering with lock on.
When I enabled “slow” mode I can see lockon being called to lock a post onto the screen, but can not see it even rendered, so the positioning is super off.
The entire LockOn class is a bit of a hack, in this case maybe instead of locking and caching a position we do something else? Maybe there is a mechanism to call lock on later after the screen is already populated with rendered topics?