Demon Prince's end bugged?

Since Demons were released there has been discussions about the Demon Prince being the most end heavy pet of all. I recently went back to my lvl 40 Demons/Dark to run him to 50 and my Demon Prince was running out of end pretty quickly. He was already slotted with an SOs worth of end redux, and I decided to frankenslot him to bump it up as much as I could. Once I hit 42 I slotted him up to 92% end redux and took him for a spin. Much to my dismay he was a little better but still ran dry in longer battles.

I started to run some of his end costs against other pets and didn't see any major differences that would cause this disparity. I then started to monitor his end bar during combat to see if the end redux was really lowering the costs and that's when I noticed something strange in his combat attributes. For some reason his end bar slowly drains when idle, even though he shows 0.00 end consumption. His end gets down to about 98.6 when his recovery tic resolves. I checked the other demons and some other MM pets and none of them showed this issue.

This small unknown end drain may not seem like much, but it looks like it creates some kind of cascading effect with how the pet uses and recovers end, causing him to suddenly become very end heavy.

Is this working as intended or is it a bug?

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Level 50s: to many to remember at this point

I just found something to add. The end drain does not start until he is given the 1st upgrade. I believe it to be Chilling Embrace that is causing it.

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Level 50s: to many to remember at this point