using Liliana, Death’s Majesty as my planeswalker, I’ve targeted the pontiff with her first loyalty ability. When he dies I get three spirits from his afterlife keyword, but Teysa does not recognize it as a black creature dying and does not award me a fourth spirit.
Added testing. Knight of the Last Breath does trigger from this interaction. So the issue seems to be connected specifically to Teysa.
Further update: I tested the pair again, and after several seperate encounters, Teysa is now triggering as she should. Please disregard the report.