12.9 iPad Pro 5th Gen. Not supporting DP monitor after a few upgrades into ios15

Why is The 5th gen iPad Pro stop supporting the same monitor it was just supporting a few months ago? I also use the same monitor and cable to run Samsung tabs and it just works without any problems. Today I thought to uses my usb-c to the older thunderbolt port adapter. Then use the same cable I run my MacBook air to the monitor. iPad recognizes it initially says need to unlock to use accessory. Unlock it and nothing. Unplugged it tried again and nothing.

I connected it with 3 different ports on the same monitor. Usb-c to direct DP works on Android Tablet initiates Dex mode. I connect it using USB-C to thunder bolt adapter to I cable going to VGA and Finally to DVI-D both cables work when plugged to MacBook Air to both peripherals listed above minus the DP Don’t have a cable for that one.

What did Apple Change in these last few updates? why did my setup stop working on the DP monitor? It still works with Samsung Galaxy Tab and the other ( 2 ) peripherals work on the Mac BookAir? This needs to be addressed. I spent so much on this 2TB 5th gen Pro.

And having to buy more equipment is not a viable option for something that was working without a hitch straight out of the box.

Did something get disabled or buried in the settings somewhere?

please advise.