hi
From the explaination avl with CCO it does says that theres some feature license mismatch in the pair which creates problem.
Error Message %FWSM-1-105045: (Primary) Mate license (number contexts) is not
compatible with my license (number contexts).
Explanation When the feature licenses do not match between failover peers, failover will be disabled.
Recommended Action Configure the failover peers to have the same feature license and then reenable failover.
since you have mentioned up about the license part which satisfies the condition of having one FO and UR in the other can you try having same IOS code in both these boxes ?
regds