Unable to run dual 4k/60Hz monitors with Precision 3581 and WD22TB4 (but documentation says it's possible)

I have a Precision 3581 with NVIDIA RTX A1000 Graphics which should support dual 4k/60Hz external displays with the laptop internal display on: https://www.dell.com/support/manuals/en-us/precision-15-3581-laptop/precision-3581-external-displays-guide/connect-external-displays?guid=guid-d3fe6c55-bace-4461-b6cf-ad97db2ccf7f&lang=en-us

The WD22TB4 also supports dual 4k/60Hz external displays: https://www.dell.com/support/manuals/en-us/wd22tb4-dock/dell_wd22tb4_userguide/video-connectors-for-multiple-display-setup?guid=guid-ff833e73-60bf-4c9b-903e-3b5a21d24b22&lang=en-us

I can run both external displays at 4k, but one will be throttled to 30Hz. If I bump the refresh rate on that one, it will then downgrade resolution to QHD. I also experienced a couple of times when waking the laptop from sleep where the external displays would not get signal (I had to toggle the display off/on to get it to work).