Infernal Legion's AOE tag not working with Rhoa Mount

I have Infernal Legion attached to my Rhoa Mount for testing purposes and I noticed that I was not able to use AOE supports like Magnified Effect, Concentrated Effect or Reach, even though Infernal Legion should give it's AOE tag to the Rhoa Mount.

The reason I think this is a bug is because when I give my Rhoa another support with AOE tag like Armour Explosion or Wildfire, suddenly I am able to use the said AOE supports with my Rhoa Mount.

There are similar weird bugs with other non AOE related skills where some supports enable the use of other specific supports but the supports with cool interactions (for example Decay support) somehow don't give their tags to the supported skills.