TrailBlazer suddenly denying chemo admin codes

Wondering if anyone else in the TrailBlazer J4 (TX,OK,CO,NM) MAC suddenly started seeing denials on (all) administation procedure codes that *are* billed with the drug HCPCS codes? Their tier II provider rep referred me to a December notice advising addition of modifier "KX" when admin codes are billed *without* the drug(s), which is not the case with our claims.