OK. So I tried out what you suggested by changing the Album Artist for the four albums to the original "Herrmann, Bernard" (1 space). So this Album Artist is no longer appearing under Album Artist node. Going to location and going to a track in the first album choosing Same as Album Artist...

No. I'm not sure where this can be found.
In any case I think that is possibly irrelevant as I can see the missing albums listed under the top level of Album Artists, even though the Album Artist itself isn't listed as a folder. So these albums are recognised by MM

Thank you Lowlander for your reply. I ran Maintain Library with complete optimization - it made no difference. It ended without any information or message. I'm not sure that optimization is going to correct errors - sound more of a performance thing. Some sort of validation function is really what i...

This is really odd. I discovered this a few days ago running 4.1.25 (I think) and having updated to 4.1.31 have the same problem. I have four albums with Album Artist "Herrmann, Bernard" except that they were no longer appearing in the Album Artist List. "Herrmann, Bernard" doesn...