This could be wrong, but it sounds like an app that is normally used outside of kiosk mode is being suppressed or disabled. If those apps work without the kiosk mode, it just sounds like something that is normally used is now being blocked, and needs to be added or allowed.
I'm not sure how you could determine what app it is trying to use, as I am just guessing, but if there is like a vpn or some check it does, that could be unavailable due to kiosk mode.
To fix it, I would simply add the app that is needed to the kiosk screen (and add it to the system apps profile, as it will almost certainly need to be listed for it to work).
I'm just starting to customize my own launcher, so I may come across more information...this just sounds like a similar situation when an app is needed to be 'allowed' for it to work.
Good luck.