I found this report (Flame Wraith Not Persisting)
It has been closed but I did not see any response to it or know if it has been attempted to be addressed. It is still an issue. Every map change I have to resummon my wraiths to have the Flame Wraiths. I have the Twin Spirits node and am using 2 2x2 idols to summon Flame Wraiths instead of normal ones.
Just want to make sure this is still on the radar or be noted if it was thought to have been addressed already.