I've attached an sample mission which simply has a unit equipped with a primary weapon, launcher, pistol, and laser designator to demonstrate the bug.
{F172281}
I understand I can use the dedicated switch weapon keys that came with the new apex preset, however I use a [[ https://www.logitechg.com/en-us/product/g13-advanced-gameboard | Logitech G13 ]] where the ability to switch between 3 weapons with 2 buttons ("switch gun / launcher" and "switch gun / handgun") instead of 3 is useful.