Changing assigned access fails

Assigned access on a Windows 10 seems broken. The client is setup as a kiosk to serve a certain webpage. I want to change this webpage, but trying to do so, gives me "Something went wrong so please try again". Of coarse trying again fails once more. Assigned access manager service crashes

I can clear Assigned access in Powershell, but then when trying to set it up again, I get the "something went wrong..."

I see others having the same issue, but no resolution other than a reinstall are suggested. Would be sad to go that way. Anyone?

Regards, Lars.