When I create or edit a post & add tags to the post using the Post Tags-add tag dialog box – the tags get listed below the dialog box as added BUT when the post is saved (or updated if already published) the tags disappear and are not added/saved with the post.
I am able, however, to add tags using the mass edit tags.
So what is wrong? How come adding tags when creating/editing a post do not get saved?
I have the same problem, but i use WPMU Version 2.84a. I thought that it is maybe WPMU related or Simple Tags collides with another plugin maybe wpSEO. I had no time to figure out if the problem could be solved by disable another plugin but i will try the next days.