The regular attack on Catalyzers do not interrupt breathing zombies, attacking greavers, or anything else with like 0 resistance to stagger.
BUUUUUT... it breaks the freeze on enemies (and probably allies).
The old Catalyzer could both interrupt greavers and put charges on frozen enemies. The new Catalyzer can do neither... and I feel like the Catalyzer should fall back into its old niche pairing with freeze for gimping enemies. I don't really care too much about interrupting breathing zombies/greavers/devilites because role that can be filled with any other weapon.

A fix to make it work on frozen enemies is to change the regular attack to deal 0 damage (as the old charge attack did). The only perks I see from that 1 damage on the regular attack are unfreezing allies and breaking blocks. It wouldn't matter that you can't break blocks that quickly because if you mentally reclass Catalyzer as a "bomb", then you realize that it breaks blocks faster than most bombs with the quick CTR.

I realize that by removing the ability to break blocks severely changes the way you main with the Catalyzer, but whatever... I'd rather have a unique gun to fill an interesting niche, than a gun whose uniqueness is spread too thinly and achieves little (Able to break blocks, but not interrupt 0-stagger-resistance enemies. More pretty explosions, but less dps cuz you can't hit anything when enemies fly every-which-way from the asplosions and Skepticraven did some maths)

With this change you would be able to put a ton of charges on a frozen enemy, put Maskeraith quills on the enemy, and have a blast while your fps plummets.