I assume we're talking about Quik Invoice Plus (the DOS version, not the Windows version).

My guess is that there are integrity errors in the archive batch(es) that are not being detected, or are only surfacing when they are fixed by Adagio Invoices. Over the last few years we have fixed several issues in the tax calculations of invoices (which might not have been apparent in your taxing jurisdiction). To the extent that a batch manipulated by Adagio Invoices prints and posts correctly from Adagio Invoices, and a batch manipulated with Quik Invoice Plus works fine if Adagio Invoices is not used, then this is only an interaction between modules running in different environments. Just stop using Quik Invoice Plus (or Adagio Invoices) to make these price changes.