Thunderbolt 3 Dual DisplayPort 4K 60 Hz adapter (Cable Matters) with AMD Radeon Pro W5700X no outputting at 60Hz for both displays

Hello

I'm using item Cable Matters adapter 107006 - the Thunderbolt 3 Dual DisplayPort adapter with a new 2019 Mac Pro with the AMD Radeon Pro W5700X module.

Adapter: https://www.cablematters.com/pc-831-131-certified-cable-matters-thunderbolt-3-to-dual-4k-or-single-5k-displayport-adapter-for-mac-windows-computers.aspx

I can't seem to get the adapter to output at 60Hz to the dual DisplayPorts - one of the 4K displays connected to the adapter is always at 30Hz. This is happening even if I'm ONLY using the Dual DisplayPort adapter and have NO other displays connected.

Has anyone out there managed to get both 4K displays connected to an adapter like this to operate at the correctly rated 4K 60Hz?

Screenshots:

https://drive.google.com/file/d/1sTNDdXLqPmD2gtkNP9pFy6eHEGGZEMEY/view?usp=sharing

https://drive.google.com/file/d/1gtzSsyffO838OotJXF7KkegddCEmyGIi/view?usp=sharing

I'm following the guidance from Apple and have tried connecting the Cable Matters adapter to Bus 1 of the graphics card, and also another Thunderbolt 3 port at the top of the rear of the Mac Pro (not directly into the graphics module).

See: https://support.apple.com/en-us/HT210968

I've also checked these resources on Cable Matters website but don't see any driver for Mac unfortunately:

https://kb.cablematters.com/index.php?View=entry&EntryID=68

https://www.cablematters.com/images/Product/files/107006/Manual/Amazon%20&%20Email/107006%20Thunderbolt%203%20to%20Dual%20DP%20Adapter%20QSG.pdf

Cheers