Steve - You're a star.
Upgrading to the B00B07 firmware has fixed the problem.
Many thanks
Dave

I don't know how to explain this but prior to upgrading the display that was displaying version B00T00, I noticed that it now displayed B00B06 and it did connect.
I've now upgraded it to B00B07 anyway and it works well.
To prove that I'm not loosing the plot, (more than normal), attached is a screen shot of the rouge firmware reported. 20221106_213314[1].jpg

I think I've figured out what's been happening.
Out of the box all the new PA32DC OLEDs displayed Firmware version "B00T00" and at this stage they won't connect with ColourSpace.
I now believe that this indicates that a firmware upgrade has only been partially installed.
With one of the displays it was displaying "B00T00" but then after a few power cycles, started displaying "B00B06"
I know I didn't load this version, so it must have been loaded at the factory but not fully installed with multiple repowerings.
That's my theory and I'm sticking to it
Thanks for your help. Dave

I'm experiencing a strange issue when switching the content I send to the screen.
When I switch from SDR to HDR the screen goes full green tinted.
The only way i've found to fix it is to change to another HDR output type eg from ST2084 1000 nit to ST2084 2000 nit. Or if i reboot the monitor.
This full screen green tint also appears sometimes if the monitor looses picture and regains picture.
I have seen this issue happen with a signal from Resolve via a Blackmagic 4K mini, and a signal via AJA Color box
I have updated to the latest firmware B00B07 / MCM103
I'm still determining what causes this issue. Any help or fix is helpful.

Also, I often switch content delivered to the monitor and the time it takes to catch and display an image is really really slow.

Also seeing harsh green edges on high contrast areas.
I will try upload some images of the issues tomorrow.

I think you will need to contact ASUS support regarding such issues.
It appears they are not associated with ColourSpace integration, and so we would have no idea on the cause/problem.

Steve