Think I've discerned the cause of this...
If you saved a SOL in 3.4 then updated to 3.6, 3.6 would create a shortcut from the old store location to the new one. This worked fine on 3.6. This does not work fine on 3.8 (for some unknown reason).
I'm going to attempt the fix Pea has described above (though also deleting the shortcut if thats possible)