This has happened to me a few times now, and before you ask yes a have the Enchanting Favor relic equipped (follower cannot die).
The Follower skill “Guardian” would proc even though you have the shielding pylon active.
I confirm, it happened to me several times too. ( and with the enchantress also ).
This happened to me as well. As a wizard, in solo greater rift, the dimensionnal shield which should prevent all damage is sometimes bypassed by some damage. I have never died with the shield active but took damage and also triggered a cheat death. It’s hard to give more details because i don’t know which specific damage got through the shield but there is definitely a bug with it. Thanks.