12/3 to disconnect box for mini split install?
Pull the neutrals out of the ground bar and join them with a wirenut
Routing neutral through an A/C disconnect is rather easy once you realize that you can splice inside it just the same as you would with an ordinary junction box.  So, all you have to do is remove the neutrals from the disconnect's bonded bar, nut them to each other with the appropriate sized wirenut, button the box back up, flip the breaker on, and call it a day!