Einhar bug (sometimes not spawn)

Sometimes Einhar just not spawns when I kill Red beast (maybe because beast stunned with gem Ruthless Support?).

Passive skill Deadly Prey not learned.

The only way to summon Einhar is move to another beast and try to catch. After that Einhar spawns and catching beasts.

https://youtu.be/Tfi0aRaPg3Y

Einhar, don't be shy :D