Just wanted to put this in text form in case someone else was having similar issues.
Recently I noticed that I couldn't authenticate any transactions using the ING banking app. After entering my mobilePin I would get a loading symbol but the app would never finish the authentication process. If the phone turned off the screen at this point due to a long idle time I would only get a black screen from the app upon unlocking it again.
After contacting the ING support I was told to deactivate the authenticator and do a clean install of the app. Note that you will need to request a one time password from ING to reactivate the authenticator which will be delivered by letter.
After reinstalling the app I made sure native code debugging was enabled and also switched the exploit protection compatibility mode on for the app before using the password to reactivate my authenticator. Now my app works just fine.
Secure app spawning is still enabled on my phone.
I can't say whether one or more of these options or maybe a combination of them specifically caused the issue but this is the way I managed to solve it in my case. Maybe the problem was needing to enable the compatibility options before activating the authenticator.