Hello, there is no ability to add / edit tags once an image has been posted to an album / category.  When you click on Mange Image > Edit Details, you can edit the fields for description, credit, copyright, etc. but no tagging.  

I recommend submitting a ticket. There is no reason you should not be able to edit tags when editing an image.

http://take.ms/yFMks

Ignore.

It was a member permission that was toggled off.