MacBook M1 pro 14-inch stops sending USB-C signal to Dell U2722DE display.

USB cables for this task must be at least USB-C 3.1 SuperSpeed+ rated and shorter than 1 meter in length. The end should be marked with that information, or a tag should be attached indicating a certified cable that meets that spec.

if yours do not have those markings, you should obtain a cable that does and try your experiment again.

As versions of MacOS march onward, MacOS is becoming more demanding about what is acceptable number of errors produced in sending data to the display. The display keeps track of transmission errors, and the Mac can read that information using the very slow secondary data channel used for configuration.

That is why my first query was about whether you were using certified cables. 'Shipped in the box' cables are often "lowest bidder" cables, and do not necessarily meet the required standards for long-term, trouble-free operation at high resolutions, where the data rates are ferocious, approaching the maximum switching speeds or digital logic.

The Mac uses a system that reminds me of “Plug and play” to determine what display is connected, and what its capabilities are.

To get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display. "No signal detected" is generated by the DISPLAY, not by the Mac.

This query is only sent at certain times:

• at startup

• at wake from sleep — so momentarily sleeping and waking your Mac may work

• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go

• hold the Option key while you click on the (Detect Display) button that will appear in Displays preferences (from another display)