Unkillable Eximus Frost MOA during weekly Clem mission

[MBaldelli]

This seems to be a one-off that left me surprised.   

I came across this bad boy MOA during my weekly run for keeping Clem alive: 

And 

He wasn't the mini-boss that typically shows up during the weekly Clem mission -- this week's mini-boss was actually the Lynx instead of one of the G3.  

Next he was of a different colour (like a darker teal or perhaps jellybean (#237fa0)) than the standard Shockwave MOAs as well as the standard frog-green MOA. 

While I could remove the frost bubble on him whenever he generated it -- this MOA was unkillable and when I removed the Frost Bubble Overguard the health bar disappeared and neither could I lock on with the Proboscis Cernos, AFuris Prime or Ripkas.  

It seemed determined to follow me and Clem around the map beating Clem into being downed.   I eventually had to move sufficiently away so that the thing couldn't continue to aggro on Clem or myself and cause me mission griefing.