Currently on MediaWiki.org, categories cannot be removed from the 'Page Settings' modal. This is true of new categories added and existing categories.
https://www.mediawiki.org/wiki/VisualEditor:Test1234567?veaction=edit
Inez says he's working on a fix now.
Version: unspecified
Severity: major
Also just checked editing a sort key — that functionality is no longer working as well. You can enter text into the field and close the inspector, but when it is reopened the text is not retained.
Change 86341 had a related patch set uploaded by Inez:
(bug 54727) item itself is an item, there is no need to try to pass item of that item
Bugfix for removal is waiting for review. Sortkey still not fixed - Trevor: Can you split it into separated bug?
Change 86341 had a related patch set uploaded by Catrope:
(bug 54727) item itself is an item, there is no need to try to pass item of that item
Change 86341 merged by jenkins-bot:
removedItems[i] is already an item, no need to pass removedItems[i].item
Marking as "FIXED"; have removed "or change sort key" from title per discussion with Inez.
Change 86673 had a related patch set uploaded by Jforrester:
removedItems[i] is already an item, no need to pass removedItems[i].item
Change 86674 had a related patch set uploaded by Jforrester:
removedItems[i] is already an item, no need to pass removedItems[i].item
Change 86673 merged by jenkins-bot:
removedItems[i] is already an item, no need to pass removedItems[i].item
Change 86674 merged by jenkins-bot:
removedItems[i] is already an item, no need to pass removedItems[i].item