I had the same problem after upgrading.  What I did find was I had some special characters in two fo my field names ('?' character in particular) that I think is part of the problem.

I used the export function to export the table data, cleaned up the improper field names, and then reimported the XML filed into a new UserDefined table control that didn't have a table defined as yet.  The import worked perfectly and it is sorted in ascending order just fine.  (I see there is a fix for the descending sort issue.)

I'm actually pleased I had a problem, because in working around this problem, I found that I could very easily maniupulate the data and feed it back into another table without having to re-key it.  This may be very useful if you have a lot of repetitive data that needs minor fixing, or you want to create a historical archive.