Logging in on Galaxy Apps (Samsung app store) failed on Galaxy S6

[Android Central Question]

I am unable to login to the Galaxy Apps app (Samsung app store) on my Galaxy S6. Got the message 'You need to login again to protect your account and keep using this service. Confirm your password' (translated from Dutch, so the exact message in English could be different).

Logging in at account.samsung.com works fine.

What I have tried but without luck:

- Deleted all updates of the Galaxy Apps app and reinstalled them
- Deleted all data of the Galaxy Apps app
- Rebooted my phone, also in safe mode.
- Changed my password

Samsung S6 Edge
Android 7.0 with latest update
Galaxy Apps app version 4.2.18.2 (latest version)