CM Old Uncleared Transactions cannot be reconciled or changed

SUGGESTED

We are trying to clear up some accounts that were never properly reconciled. There are several transactions from past years that we need to mark as reconciled. When we attempt to change them in the Edit Register, we get an error that says:

Could not determine if 12-19-2018 is in a closed GL period for prefix 1.

Anyone know a work around for this issue?

Thanks,

Warren