It looks like the freeze from the melee is cancelling the poison status. No damage over time form the poison once the freeze fully activates. If I get a final blow with PB, the poison spread works. If I get a direct hit that is not a final blow, the poison can be seen for a few frames before the freeze kicks in. But the frozen animation removes both the poison animation and the DoT ticks. If I get an indirect splash hit with PB, the target is not frozen, and takes poison damage until the poison runs out. Hopefully someone else can replicate/corroborate these issues with the melee interacting with this exotic. Edit: When I get a PB final blow that spreads poison and creates iceflares, the iceflare bolt that finds a nearby poisoned enemy will freeze and cancel that poison status. This is what lead me to believe the freeze status is conflicting with the poison status.