When closing a selected tab (A) next to an unloaded tab (B), B is briefly selected and gets the loading icon, before another tab (C) is correctly selected

[l10nelw]

B remains unloaded but retains the loading icon indefinitely, until manually selected and loaded.

Happens with the "Prevent Firefox from loading unloaded tabs" option enabled.

[NiklasGollenstede]

Sorry for the late reply. This is a known Issue, mentioned on the post-installation page:

Preventing tabs from loading doesn't always work completely. This is due to the way WebExtensions work. They report things (like the closing of a tab) asynchronously, that is, after it already happened. Sometimes (often randomly) that is too late. In these cases, UnloadTabs tries to revert the default actions, but that may not always work entirely:

• Tabs may loose their icons or display as loading. These are Firefox bugs. Reloading the tab fixes the problem.