1.18.1
So I manually added a custom keybind and then set keys to each option.
First bind is for "zoom" option from optifine.
Second bind is for inventory sorter mod.
If I restart the game custom keybind disappear from the list, and I need to add and set them again.

Settings persists only in file, but doesn't show up in game or do anything at all.

key_adapters.properties
#Key Adapters
#Tue Dec 21 03:41:50 GMT 2021
key.categories.misc=controllable.button.dpad_right
keygroup.inventorysorter=controllable.button.select

Thanks.

I have the same problem, I am making a mod pack with my friends, and whenever I add custom binds, they are gone.

This is fixed in the next version. Thanks for reporting.