just got my 8K today (backer 773) and I thought I’d screwed it up already!
I have a 4K and still have PiPlay. 8K was working fine until I changed modes in PiPlay to Video mode. Changeover failed and so did the 8K
Tried everything - unplugging 8K, changing DP sockets, re-installing Piplay and Pitools. No joy still got red light on 8K and disconnedted warning on DrPi and Pitools.
In despiration I unplugged the 8K and replugged in the 4K. 4K display gave me the expected stereoscopic view. Opened PiTools which now told me that I had an unsupported mode (Video) and did I want to resolve - YES !!! Changed back to Pimax mode. Replugged 8K and it works !!!
So it seems that changing modes in PiPlay with the 8K screws up the 8K but there is no way to get back without using the 4K