Running MB 3.5.8698
I have an auto-playlist defined with one match condition:
Artists: Remixer = has a value

In version 3.5.8447, this resulted in a playlist with about 850 tracks:

After updating to 3.5.8698, the playlist is empty:

I've tried the various other Artists:xxxx rule options as well and they also appear to fail to match any tracks after updating to 8698.