I've a couple of Activities, the default "Desktop Icons" activity, and another.
Both activities Desktops are configured as "Folder Views" - the "Desktop Icon"'s Location is "Desktop" (AFAIR the default setting), and the other's is a "Custom location" which happens to be a folder on the Desktop.

The contents displayed for each of the two activities tends not to be updated properly, and sometimes vanishes completely when I switch from one activity to the other.
Specifically:

1. if I create a new file in the Custom location, it doesn't appear on the desktop for that activity, even after clicking on Refresh desktop. The only way to get it to appear is to switch the location to somewhere else (say Home) and then back.
2. sometimes after switching from one activity to the other, the desktop is empty - just the wallpaper and the task manager. Again, switching the location to Home and back makes the folder's contents appear.

Any suggestions on what might be causing the problem?
(My system says Folder View 3.0 under "About"; software levels Plasma 5.21.5, qtcore 5.15.2, xorg.server 1.20.13, distro Gentoo.)