In Reliquary's Heldrake boss arena, I found a spot where the player can get stuck behind a pillar. It is the pillar to the right of the central activation platform. There's a small hole between the pillar and the ground where I got stuck and could not escape. Regular dodging and Assault jump=pack dodges in multiple directions did not free me, nor did finishers, melee attacks with the power fist, explosions, or parries. The Assault jump pack flight ability would not activate in that location and the targeting reticle for the jump pack disappeared.