Chances are you can be equally assisted by the solution from this thread:
https://www.vbulletin.com/forum/show...=1#post2170134
I had the same problem, and it solved the issue. Basically, you're probably using a custom theme, which has a separate folder for the editor images. As such, those are different from the new editor, and a brute force fix is to simply copy all the buttons/images from images/editor into your theme's 'editor' folder.
I wish there were a way to revert to the prior editor, as this 'new' editor has also broken a bunch of other plugins' functionality. The lack of QC testing by vB devs, lately, is bordering on extreme frustration, though I doubt that will change, sadly (exasperated sigh!)