I believe you should be able to, I certainly can with my elevated account, but I don't have a regular account which has old Sims content.
Can I check what you're trying to edit? I assume it's editing in updated pictures to the Whittaker Saga, in which case, can you try editing just text first?
Also, just to double check, from your description it sounds like there's no flash of an error or page highlights, Publish is clickable but non-responsive. Is this the case?
Editing in a potential fix: From investigating, this seems to happen when there's a hyperlink contained within spoiler tags. If anyone finds themselves unable to edit, please check for this within the post, and change as appropriate.
We've submitted a bug report on our end for this too.
Thanks.