Penta Causing Damage To Sentinels When Fired Above Ground Level

[TiredZombie]

I've just been doing some dark sector defense runs on Pluto - Sechura, and noticed that when I'm above ground level, my penta will damage my sentinel but not me.  Regardless of range the grenade it detonated at, my sentinel will receive damage.  Whether or not I have a firestorm mod on my penta has no effect.  I could be well outside the blast radius, but my sentinel can still receive some damage and I won't.

 

When I'm on the ground, it seems to be fine.  When I perch myself on a ledge, looking down, that's when it goes a bit wrong.

 

Anyone else noticed this?  Not to sure if it happens will other explosive type weapons.

[TiredZombie]

After doing some more testing, I now suspect it could actually be the Volatile Runners are the real culprit.  When I kill a large group of Volatile Runners, they blow up which doesn't do damage to my frame, but to my sentinel.  Can anyone else confirm this?

[tmagict]

I've tried this in different missions with different fractions. The explosives are the one killing sentinels and kubrows. First it take down the defence then followed by hp. Tough it's still not 1 hit kill.