Latest version did not fix the page not turning issue but I didn't see any failures to clear old page content and draw over it anymore (as of yet).
Apparently, its somewhat known
issue due to PB device auto-suspending in the middle of page turns.
From the looks of it, somebody needs to add PB API call to disable suspend during page turns and then re-enable them after the page has turned. And the same for navigating the menus etc.
Since Coolreader works on this device they probably do it either right or just disable auto-suspends and consume more battery.