Occurs in Selena and Diana. Open plugin manager. Make sure you have some installed, but disabled plugins. Switch to Available page. Enter a filter. Tested cases when the only plugin matches filter: "jar ma" for "Jar Manifest", "perm" for "Permute Plugin". Select this single plugin and install it. This is done. Switch to Installed page. It is empty (all is filtered out). Click in the white field. Switch back to Available. See green installed plugin. Ok. Agree to exit IDEA. Restart IDEA. See that all installed plugins become enabled. I'm not sure is this related to clicks in the white field, switching tabs, or maybe the specific of "Jar Manifest" and "Permute Plugin". But this happens regularly and repeats with provided scenario.