I figured out the issue and I thought I’d document it for anyone else that runs across this.
The issue is in the RDD.
In my case this Report was a custom report that needed to pull in CSF UD fields which during the last upgrade somehow broke the RDD, where the RDD removed Data Source tables I had added but still kept the Relationships. So this error was thrown on a missing association in the Relationships. I just had to add the two missing tables and the Report started working again. Good reason to always backup the RDD’s? They might be able to reimport in a future version… maybe? If not, you can still read/compare the backed up RDD xml to the current running RDD exported xml to determine any differences.
This same error could also be raised in previous versions that used Crystal Reports because it’s an RDD issue:
Sequence does not contain no matching element while running crystal reports - Epicor ERP 10 - Epicor User Help Forum