I was able to replicate this error when I was analyzing a cube with dimensions that had a "." (period) in their names.
Analyzing the cube against a replica cube, with dimensions without the "." in their name worked fine.
This is the same issue that we had with the first release of Universal Reports.
IBM do not seem to like testing with "." in the dimension names, even though they are not listed as a restricted character in
https://www.ibm.com/docs/en/planning-analytics/2.0.0?topic=development-tm1-object-naming-conventions
Paul