Mac Studio with Dell U2723QE x 2 -- which USB-C Cables?

I just purchased two U2723QE monitors for my brand new Mac Studio. I chose these both for their image quality and also because a single USB-C cable can carry the image signal to the monitor, as well as power the monitor's fairly extensive internal USB dock. They monitors work great with the 1-meter USB-C cables that shipped with them. But due to my two monitor setup (and the computer being off to the right of the desk), one of the cables isn't long enough. I purchased two cables to try:

1. 6 foot Anker 100w USB 2.0 Type C 

2. 4.9 foot Spigen 60w USB C to USB C Power Delivery Fast Charging Cable

Both cables work to power a USB-C, bus-powered drive. But neither of these work with the monitors. No signal available. I'm connecting correctly, because I'm currently using the monitor with the cable Dell provided, but I need something at least 4 feet, ideally 6. Is anyone familiar with this predicament, and if so, have you had any luck with longer USB-C cables?

Thanks!

TC