Map Atlases version: 1.19-5.5.0-all
Moonlight Lib version: moonlight-1.19.2-2.2.46-forge
(I am also using Supplementaries version supplementaries-1.19.2-2.3.24.)

Crash log.

Swapping an Atlas in your offhand with the item in your main hand and then scrolling to another hotbar slot crashes the game. The world will then consistently crash on startup until and unless you change the activation mode to something else; I tried "Hands & Hotbar" which solves the issue.

Steps to reproduce:

1. Change the activationLocations config option to "HANDS".
2. Place an Atlas in your offhand slot.
3. Use the Swap Items In Hands keybind while you have another item selected.
4. Select another hotbar slot. The game will crash, and continue to do so on startup.

is this still an issue in latest version?

Yes. (Tested with different items but identical method as before.)

It also seems worth noting that on a different occasion I switched my config off of "Hotbar & Hands" to just "Hands" while an Atlas was nowhere near my hotbar, so it couldn't have been active at all, and the game still crashed as soon as I unpaused it.