Out of all my rackspaces, only one has Blue3 (two instances). When that rackspace is active, it has started “crackling with audio drop out” only on Blue3 (for 2 seconds) recurring every 20 seconds. If I bypass both Blue3, the crackle crackle/drop out stops. THE OTHER INSTRUMENT IN THE RACK (Kontakt piano) continues to play fine DURING the crackle.
So I think the problem is isolated to the Blue3 (the only VST affected).
SOLVED: My license somehow has changed to demo after a year. I did purchase a licenses so I guess I will try finding and entering the code.