Some Tracks not Appearing after Tagging

[Budgie]

Been doing a bit of tagging house keeping on my opera collection which is stored on Qnap NAS and served by minimserver to Bubble DS control point and thence to DS renderer.

My tagging session was intended to clean up errors and tag omissions in various fields and once done I have uploaded the revised works to the NAS and rescanned.

The BubbleDS display on my control point is working as usual and OK but now one or two tracks are missing. I have repeated the recscanning and cleared cache etc. I have checked the tracks are all present on the server but cannot see what I have done wrong. Please could somebody advise.