Dell U3219Q does not detect after macOS 12.1 update

Number:rdar://FB9809866 Date Originated:2021-12-15
Status:Open Resolved:
Product:macOS Product Version:12.1
Classification: Reproducible:Always
Immediately after the macOS 12.1 update my two Dell U3219q displays no longer are detected when connected in USB-C mode. If I connect to them over HDMI or DisplayPort (via USB-C) they work, but the USB-C charging + display mode they only detected as a charger and show no picture (black screen, searching for signal).

I believe this was likely related to the changes around USB-C charging + display listed in the release notes as “External displays may not charge some MacBook Pro and MacBook Air computers when connected using Thunderbolt or USB-C”. This broke my critical workflow and there appears to be no viable solution beyond connecting over DisplayPort instead.


Please note: Reports posted here will not necessarily be seen by Apple. All problems should be submitted at before they are posted here. Please only post information for Radars that you have filed yourself, and please do not include Apple confidential information in your posts. Thank you!