Clearinghouse denial: entity code

Need help troubleshooting a clearinghouse rejection. Randomly, there is a 3 week period in which a large portion of my OP SUD Ucare PMAP claims are getting rejected citing   ":ENTITY'S SPECIALTY CODE, ENTITY'S SPECIALTY, TAXONOMY C
ODE.:ATTENDING PHYSICIAN"

I cannot figure out where this is stemming from. Nothing has changed w/our clinicians, billing, coding etc and the taxonomy code is the same as it has been. Strangely, this was only an issue for a few weeks in April.  Did anyone else have this issue?  Solutions?