I have recently experienced this, though do not wish to test the reproduction of it. (Seeing as it may be in relation to the invulnerability granted from using sparks of life)

Recently (On the Grinchlin mission if that matters) I used a spark of life and immediately charged a bomb to place in between the 4 enemies that were surrounding me. Upon releasing the bomb, it never hit the ground and instead forced my knight into the bomb drop animation over and over, without the ability to move in any direction (unsure if this was due to unit collision from the enemies surrounding me, or the glitch itself). I may have or not been hit exactly when trying to drop the bomb as well. I do not believe that lag was involved in this situation.