Hi Rick,
I was having some issues with Adagio Payments credit card fields the last couple days on one of my client's systems. Although they are not necessarily related and I did not receive an XML error like you, the solution I found is an easy one to try.
In my case, (another dealer's experience showed this too) the Entry Templates in AR needed to be adjusted. In AR under the Edit menu, go to Entry Templates and go to the Cash Entry tab. Select or deselect any of the fields under Disable. Click Okay to save. Then go back in to the same place and change the selection back to what you had it.
In my case, on two entirely different installs of Adagio on two different data sets, a change to the Entry templates made our issues with Adagio Payments "go away" immediately after we made the change.
As much as I wish I could say exactly why that's the case, I can't. But since it's a very simple thing to try, I thought I'd offer it up as an option.
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Dan Desautels
DezTek Solutions Inc.
Thunder Bay, ON