Even if the computer system allows it to be filed, the DOL can still reject the filing.
I think it's a risk, but I guess you can try.
What the CPA is suggesting used to be done often prior to electronic filing.
I would be more likely to just not file and do a DFVC later.
I don't have an answer. However, when I have any unexplained browsing issues, clearing cash, deleting temporary Internet files, and rebooting PC sometimes helps.
In my opinion it is not real estate. We report that as "...assets whose current value was neither readily available..." and file a 5500 with Schedule I.
Never use a check as a bookmark!
If you can verify you had such a plan and participant, reissuing the check will cost less than asking legal counsel what you should do.