Hera Syndulla Focused Datacron LVL 15 states :
At the start of the encounter Hera Syndulla and Kanan Jarrus gain Guard until they are defeated. Whenever an ally is defeated, if there are no other allies with Guard, Hera applies Guard to the strongest other Phoenix ally.
From the attached image named X1 you can see that hera and kanan has guard. Kanan dies while having backup plan from Hera which makes him revive.
From the attached image named X2 you can see that kanan revives but hera does not apply guard again to kanan or ezra ( depending on how the order is ).
So in conclusion Hera FDC LVL 15 is not working as intended because when kanan dies there are no OTHER allies with Guard ( just hera has it ) so it should trigger and give kanan or ezra guard but it does not.