I have been running several events on a level 70 char, mentored and original level depending on zone events and time elapsed on events.

Farming events, I use my portal recalls from the planar attunement and the portal recalls from the artifact sets (IPP, Stillmoor and Shimmersand)

I came across a lot of portal recalls failing,
Mentored, not mentored, flagged, not flagged..

One of the issues seemed to be recalling from one map to another... So recalling from brevane/dusken maps to vanilla maps.