I have created bug reports in game, but i'll post whats happened here as well.
Was doing the deferi missions for easy EC, and used my cannisters on 6 npcs. The cannisters did not slow/snare the enemy at all. Then i used it on another set of enemies in a different mission, no snare/slow and then when detonated they didnt recieve damage from it.
I have the health bar floater over enemies so i know how much health they have, and theirs didnt drop at all.