I am experiencing a similar problem: same error message on submission, like you I have no outstanding empty field, even tos and privacy are filled, and I have re-uploaded images for good measure, with no luck.
Sorry about that, it seemed to me if Francesco had not replied he might have found the solution and could share.
I have tried logging in and out of the dashboard, with no change
I have tried removing all information and them filling back in
I have tried creating a new version from scratch -not from cloning the last one- and filling in all fields (I also installed and ran this new version on my channel as is required)
“Missing Required Information: You are missing some required information. Please go back to Local Test and fill the fields in Version Details marked with *.”
All fields in Version Details marked with * are filled in.
Even fields without * are filled in.
Summary and Viewer Summary are well under the 140 character max
The Description field is well under the 1040 character max
General Category is filled.
There are no more than 15 categories entered.
Also re-uploaded all images and saved all changes multiple times in both sections.
Beyond the Version Details tab, all the fields in all other tabs are filled appropriately.
Even re-uploaded the assets files.
Moved to hosted and tested. The extension works fine.
Nonetheless, “Submit for Review” results in the “Missing Required Information” error.
I imagine there’s a quirky detail somewhere I’m overlooking.