Hopefully Susan will pop by and confirm.   IMO, a MD resident would owe no (additional) tax to DC and would likely not even have a filing requirement.  The entity paid the tax via the D-30.  That tax should have been deducted at the entity level (but maybe not until next year if cash basis) so it doesn't even count against your $10K SALT limit.

I'm not sure why PS would even generate a DC K-1, I'm curious as to what Lacerte does in these circumstances.