I can confirm this is also an issue now on the 27" 4k Dell S2722QC
The docks built into this monitor are fully standardised docks, like the WD19, WD15 etc.
Totally compatible with HP, Dell, devices, even Android USB-C phones with display capabilities, however Apple, somehow have either a physical flaw in this series of MacBook or a major software driver error for the display / thunderbolt interface, yet it remains unpatchd.
This stuff is standardised. This is absoloutely an Apple fault, not a Dell / Thunderbolt fault. Heck my iPad Air 4 works on these docks.
Topic:
App & System Services
SubTopic:
Core OS
Tags: