So let me get this straight; ANY time in PvE where we get knocked out while entrench is up; we should report it as a bug?
It might be easier to list the enemies against whom it does
I know for sure the imperial quest on Alderan where you have to slow the assault on the outposts and get the droid chips (which you return to house Thul and find an attack under ground afterwards), the commandos fire rockets at you that make you bounce out of cover, even with entrench on.
That quest is called Multiple Fronts
, and the mobs that use the knockback missiles are called Guerilla Commandos. They come in packs of 2-3 or so, so as a sniper getting repeatedly knocked back without anything to do about it, especially since we're only in the upper 20s and still heavily reliant on Snipe for damage, it's pretty frustrating and quite easy to die on that quest (even if you know what you're doing).
Just a few other examples of Entrench failing to function, off the top of my head:
- Yadira Ban's pull (Cyclone Nova) in Black Talon.
- Chief Engineer Kels's knockbacks from the electrical generators in Boarding Party.
- Everyone's favorite: the Infernal Council guys in normal mode Eternity Vault (not hard or nightmare mode, for whatever reason -- just normal). I actually suspect this was the "cover integrity" mechanic that was removed in 1.2, but I haven't had a chance to try EV on normal mode to test it out yet.