Problem with Harrow + Oberon on Eidolon Hunt group

[MPonder]

So I was trying Oberon instead of Trinity because of the Smite Infusion augment mod with 210 ability str.

https://warframe.fandom.com/wiki/Smite_Infusion

So I buffed chroma, but every time the Covenant invulnerability phase finished, the buff disappeared from the UI from Chroma.

Anyone know if this is a bug, some UI problem, or anything that I might not have caught while reading Harrow ability.