Thank you @v-yuazh-msft!
So I think I was mistaken regarding what was causing the error. I realize now that I am getting an error on the condition because the ensuing action is failing. If the condition succeeds, the Move Email action should run, which takes the Message ID from the "When a new email arrives in a shared inbox" trigger and moves the email to the specified folder (see initial screenshot above).
Here's more detail on the error:
The specified object was not found in the store., The process failed to get the correct properties.
clientRequestId: 706ee073-9726-4259-869b-adb6642c4a4a
serviceRequestId: 2604d23b-4418-4dcb-a5ba-c0ea98a9c490

So, i believe the condition is working find.
I did some research on the "Move Email" action but haven't found anything yet that explains the error...
Any ideas?
Thanks again,
- Kurt