Trouble with mission 7

Anyone else find the wave part of the seventh mission on the story me and in a team of 3 cant seem to defend it because something seems to do ■■■■ tones of damage to it.

just be careful with those smaller size enemies, so annoying

Yup, brick walled here 3x playing online with randoms. And then The Sentinel glitches in another mission if you destroy the shards too early, becoming invincible. 2 unplayable missions because of this =(

Not complaining about the overall game.