also, did you get your radios aligned? any used radio, especially of unknown provenance/vintage, is suspect to having tuning issues. The XTS series are often built from canibalized units, by persons who know just enough to be dangerous. Unless one has been at least run through an auto tune on an R8000 or 3920 or similar service monitor, even if only off a couple hundred Hz, it's enough to drive things like PL/DPL decode and P25 performance crazy. If you're confident your programming matches the bandwidth of the system(s) you're listening to, both those radios might be needing alignment.
FWIW we do alignment every year on the radios on our system and use a specialized piece of hardware on the radio system known as a DiasnostX to locate radios that are off frequency or high bit error rate. All radios go out of tolerance over time. Even ones brand new out of the box.