Have you uninstalled then reinstalled it from the Play store?
Oreo is not yet released for the Note 8, so I am assuming you installed the leaked version from February 3rd. Xerox has not had the chance to test it and I can't run it on my S8 plus because its the Exynos variant.
I can say the Print portal opens fine on the Pixel and Pixel 2XL which both run 8.1.0, so it would appear to be a your device, or Samsung issue more than an Oreo problem. Sadly there are not many models I/we can test on, but we unofficially have quite a lot of Nexus and Pixel devices here as personal devices in the test environment, I've not had any issues from co-workers reported as yet.
Hello everyone! I've been using the Xerox Print Portal app on my Note 8 for a while now. It was working just fine when my phone was using Android 7.0. Today that I updated to latest Android 8.0 whenever now I am trying to open the app it is only loading a white blank screen on it's startup and simply closes itself after few seconds. Can anyone please help??