There seem to be two solutions:
Revert the software to version 24, instructions and download are in this thread at position 13
Revert to 24 and stay there
Use Steam VR Beta, instructions are in this thread at position 141
Steam VR Beta
Your mileage will vary but I’m very happy with the Steam VR solution. No fiddling with files, you can stay current with Oculus software, including Betas and there are no flashes at all, none. Performance seems very good - better than V 24. One other plus and one minus. Plus: You can Alt-Tab out of the VR window, no need to disable VR to look at a map for example. The minus is that if you take your headset off, it doesn’t reset the view .. which might be a plus come to think of it.