Ultrawide Monitor Flicker at Refresh Rates over 60Hz Docked or Through dGPU

Hey all, I’ve been loving my FW16 for the last few months, but finally pulled the trigger to replace my dying desktop with it full time. I picked up a Cable Matters Thunderbolt 3 dock (107044) and noticed that it had trouble running both the ultrawide at 3440x1440 and my second monitor which is 2560x1440. Only one or the other would display, with the other usually showing No Input or it would display, but flicker really badly.

To test, I picked up a Thunderbolt 4 to Displayport cable (also from Cable Matters) and connected the ultrawide directly to the dGPU USB C port with the other monitor connected through the dock. Now the other monitor is working just fine, whether it’s set to 60 or 75Hz, but the ultrawide continues to flicker if I set it to its native 100Hz. I have to set it to 60Hz for the flickering to stop.

A couple of points of note: Flickering in this case means full screen blackouts one to two times per second for roughly ten seconds before a reprieve of a few seconds before it starts the same sequence again. The sequence doesn’t change if I set the refresh rate to 85Hz.
I am running Windows 11 and setting the refresh rate in Settings. The ultrawide is G-Sync certified, but Adrenaline states it’s not compatible with FreeSync somehow. There is no setting in the monitor itself to turn adaptive sync on or off.

Thanks in advance for any help.