Issue w/ Macbook not recognizing Monitor that Previously worked fine, not due to OS update

anthonydig4010 wrote:

The portable monitor is still receiving power and when I plug in the HDMI so that both cords are fully plugged in, the monitor even recognizes the HDMI but does not display the MacBook screen.

If the monitor shows up in Displays Settings, have you checked whether it is set to run in extended desktop mode? I'd expect a second monitor to have nothing on it – no menu bar, no Dock, and no windows until you dragged some there – in that mode.

Extend or mirror your Mac desktop across multiple displays - Apple Support (CA)

Amazon – WGK Portable Monitor 14 Inch FHD1200P Ultra-Slim for Laptop Monitor

According to Amazon's description, this monitor has "2 Full-Feature Type-C ports." It doesn't sound like it should matter which one you use – but have you tried both of them?

you need to run your experiments very carefully.

The Mac does not rely on Windows-like side-loaded "Drivers" which are actually packages of resolutions and settings for a specific display. Instead, it goes straight to the immutable source -- it asks the display itself.

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)