Is this only happening when you play through the third person character?
If that is the case, it has to be an issue within character blueprint itself. I would try turning up your post process blend weight again, back to 1.0, but making sure it’s priority is not overriding your world post processing.
I honestly can’t help you much further unless I have the project in front of me, so I can dig in and find the root of the issue. If you can share your project, which we always handle with the utmost privacy, you can do this by uploading it to google drive or dropbox and sharing the link with myself in a private forums message.
Thanks,