Why are my plugins installed but not visible or selectable?

For several days now, my plugins are no longer displayed - the plugin list remains empty, as if I had not installed any.

When I click on “Manage plugins”, the message appears that I have no plugins installed.

But if I then click on “Browse plugins in Community”, all my previously installed plugins are shown as already installed.

I have already tried the following:

• Uninstalled plugins and installed them again.
• Tested in the app and in the browser version.
• Quit the programme and restart the computer.
• Waited one day

Last week, the plugins were suddenly loaded again (one after the other). Today they disappeared again.

Does anyone have the same problems and is there a solution?