All Blackmagic Design cards are finicky.
There is an art to making them work.
It is possible to encounter motherboards that simply will not work with them under WDM / WATCHOUT.
While the BMD utility will confirm connections, it does not confirm the WDM driver.
i.e. Their utility uses their proprietary driver which tells you nothing
about the function of the generic WDM driver required by WATCHOUT.
Buying five of anything without first testing a sample is a very risky approach.
Your experience is a good example of the value added by Dataton WATCHMAX
or the VARs who specialize in WATCHOUT tuned hardware.
Looking at the straight hardware cost underestimates the value of tuning and testing to insure compatibility.
The configuration process can be very time consuming and challenging as your experience shows.
I know of one WATCHOUT specialized VAR using the Intensity Pro 4K with WATCHOUT successfully,
And it took them many days and a many, many hours of research and testing to get it working correctly.
I was hoping they would volunteer their knowledge here, but that does not appear to be the case.
I can understand their reluctance to share what they learned,
that is the added value that justifies the increase in price the WATCHOUT specialization demands.
i.e. The preparation and after sale support are what add to the cost of their WATCHOUT offerings.
So when you look at a WATCHMAX or a WATCHOUT specialized VARs offerings,
consider not only the hardware cost, but the time required to make that hardware function reliably.