Hi Richard,
Very pleased that merge albums worked for you here but I would raise a word of caution about using it repeatedly. There is an insidious bug associated with merge (or fix track grouping) that occasionally strikes and has the effect of involving an earlier merge target in a later merge operation, resulting in a terrible mess. It recently struck another user and is undergoing active prioritised investigation.
When I was ripping multi-disc CDs I was able to work around the bug by restarting Roon before conducting any merge operation. That seemed to purge the old target from Roon’s memory. I would definitely recommend doing that when conducting multiple merge operations.