It started working again. Iāll wait to see if the bug comes back and try to see what the circumstances are. But for now I canāt reproduce it, either.
The bug disappears whenever I make a new file. It reappears whenever I press pagedown. So steps to reproduce would be
create a new file
enter several non-empty lines, move cursor to beginning of first line
press pagedown
bug 1 cursor moves to end of line 1, instead of moving to bottom of page, as pagedown should do
use arrow keys to move cursor down a few row and to beginning of row
press up arrow key
bug 2 nothing happens; cursor doesnāt move
this bug 2 applies to all my documents
if I create a new document, the bug goes away until I use pagedown again.
Itās possible other actions can also trigger / remove the bug in additon to pagedown and creating a new document; these are what Iāve noticed so far.