@Tony,
Thanks for all the information. At this point, I don't think there's a reliable solution. I've done the VBA cleaning that I discussed in previous posts and had some success. I've distributed updated files to about 30 users so far and it has worked for all but four. However, I've had two users contact me today where it worked initially but stopped working after a couple days.
Rolling back to the 2211 update is the only realistic solution. I've had a lot of success having users check the "Disable Trusted Documents" checkbox in Excel's Trust Center Settngs, which forces the user to click the Eanble Content button each time. Anything that will allow the file to open completely before VBA code starts running. That seems to work unless the user has the Excel vba window open, then they get the error. I can't really explain why that would be the case and I'm not sure if that would work for your files.
It's getting really annoying as I have hundreds of users and every day more of them get the Office update and have the problem. I just wish Microsoft would pause the roll out. I'm tired of spending my days trying to find workarounds for their bad release. I hope someone in Redmond is at least paying attention.