New Weapon/Armor/Concelhaut skull active abilities sometimes not showing up

This has been happening for a few years since v3.9.3.88783:

Often when finding and equipping a new unique weapon or piece of armor that adds active abilities (ie: concelhaut's skull adding a summon concelhaut button), the ability just doesn't show up in the combat menu. It persists no matter how many times I equip and unequip the item and move between different areas/reload save files.

Fortunately, the fix is pretty simple: just exit to the main menu and reload the save from there. This fixes the issue for that particular armor/weapon you have and you can equip and unequip it just fine after that. It only seems to happen when you find a new weapon/armor for the first time and use it in the same playthrough. Here's a list of the weapons/armor I've had issues with:

Stormcaller and it's bulwark against the elements

Concelhaut's skull pet and its ability to summon concelhaut

Bittercut and its infestation of maggots ability plus it's other one too

Deadfire cannoneer's belt and its various abilities

It's really dicey when you're doing an Ultimate run and you've already entered combat and realize the ability you need isn't there!