I had occasion to call the DOL Office of the Chief Accountant regarding post-year transactions for a final Form 5500 -SF filing.
A terminated plan had issued $159k of checks for a rollover that did not clear on 12/31/16, but did clear in January 2017. They advised me to file a final, showing a payable that offset the cash on hand, thus reducing the net assets to $0. They also recommended attaching a letter of explanation with the EFAST filing.
They said I might get a warning, but not an error.
EFAST filed yesterday, Received a warning, but the filing was accepted.
So far so good.
Hope this helps.