It would be kind of pain in the neck, but I wonder what would happen if you made a new Smart Group with a name that's not even similar to another smart group you have.  It sounds like you're looking at two different Smart Groups, which shouldn't be the case I realize, but I might take a handful of the computers and make a new Smart Group and start adding to that a few at a time.

Thanks Ajay - I tried that, but get the same. However, now I have three profiles that show the same number of assets, but two that are both different.

I've recreated the two different ones, but no joy.

Just to round this off. I've used an inverse smart group in the exclusions list and this seems to have worked. Not sure why...but it's all good.

Excellent work around.  I’ll have to remember that.