Marc:

There is a known issue with reversing cheques when the transactions are in history. Hopefully you have a pre-reversal backup that you can restore, as the transaction is gone I'm not sure if the data can be repaired. Alternatively your Adagio consultant can help you sort this out with a manual entry.

Hopefully we will have a fix soon. In the mean time my recommendation is to not run period end in AP until this is fixed.