Hi PowerPros Drones,
We have seen a few issues such as this come into support recently; can you try uploading an image in ArcGIS Online under Settings > General > Shared Theme > upload image and see if this resolves the issue?
If this doesn't fix the problem I can assist with getting a case created with Esri Support.
Thanks Peter Klingman! This was an issue we were having also. I had already had an uploaded image present so I navigated to Settings > General > Shared Theme > Manage shared theme colors and changed the header background and text colors. It fixed it as well. Thanks!!!
Thank you @Peter_Klingman I had this exact issue. After weeks of searching support forums, trying different things and going through the hectic trouble of re-installing and restoring of ArcGIS Portal, this was the only thing that worked for me. So simple, yet brings WAB to a halt!
@Peter_Klingman this need to be raised as a bug for Portal 10.8.1. Please could you confirm it has been raised, if not, then I can oblige.
Hi @AbelE this bug looks slightly different from the one that was in ArcGIS Online (setting a logo vs. not setting a logo in the shared theme). Further, Portal 10.8.1 should have picked up the fix for this bug in Online, so my hunch is that it's a slightly different issue with a similar workaround:
If this looks like what you ran into, send me a private message with your customer number and I can get your account attached. If it's not the same, then I would recommend getting in touch with Support and raising a new bug.