This is ridiculous.
We're developing an app for a small organization where all devices are personal. Already it proved surprisingly convoluted to distribute the app internally. Finally we found the Redemption Codes solution - which btw still feels like a workaround - somewhere on the web, because in Apple's docs it wasn't clear at all.
So after all the hoop jumping for weeks now it turns out noone can install it apart from employees based in the specific country registered in ABM (which is almost noone).
What the frack??? Especially now when most companies are doing a lot of remote work how do they expect everyone to be in the same country?
Possible infinitely ugly workaround (not tested yet): instruct employees to temporarily switch region to the desired one in their device/iCloud/appstore whatever. (yes I know but at least it might work)