Two of the same monitors showing different resolutions

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)

The Apple standard for its built-in hardware-accelerated displays, makes them suitable for full-motion video for production/display of cinema-quality video with NO dropped frames, and NO dropouts or partial-blank scan lines due to memory under-runs or other issues. This requires a hardware rasterizer/display-generator for each fully-accelerated display, supported by Huge memory bandwidth to refresh each display 60 or more times a second. 

NB>> If any transmission errors are detected, such as by signal deterioration from using cables longer than ONE meter total length without signal re-driver circuits, the display resolution may be reduced or the display may drop out entirely.

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The Windoze standard for its directly connected displays is,

"Set it manually to whatever you like. If you think it is OK, then it is!"

Boss_Chonk wrote:

Connecting one LG monitor to the Mac Studio and one to the KVM switch did nothing - one monitor stayed 2560x1440/180 and the other only 1920x1080/120 that I could force to 2560x1440/180. However plugging both monitors into the Mac Studio allowed both to show up as 2560x1440/180 natively.

So it appears to be some conflict between the KVM and macOS since the KVM works fine with Windows (as both monitors show up natively as 2560x1440) - so both ports on the KVM I'm using for monitors have no issue handling the resolution (as the KVM is rated for dual 4K@60Hz or one 5/6/8K@60Hz and one 4K@120/144Hz) and the cables can handle the load as well. The KVM is marked as being macOS compatible and it worked fine with my Apple Studio Display (5K@60Hz) and one LG display (2560x1440@180) in my initial configuration.

I'll have to contact Sabrent and see if they have any ideas. Or just get a second Studio Display and find a KVM that can handle dual 5K@60.

Good luck.

Let me test my understanding:

You are using TWO Thunderbolt cables from the BACK ports on the Mac Studio to the Sabrent box. These cable have the genuine Thunderbolt symbol on them and are 0.5 meters or shorter. (In this case ONLY, the cables included with high performance KVM/Switch of length 0.7 meters are probably just fine.)

from the Sabrent box, you are using Brand-X USB-C to DisplayPort adapter/cables to the displays. These adapter cables are no longer than ONE meter each.

Your displays support DisplayPort 1.4, so they could transmit directly on a ThunderBolt cable using DisplayPort-HBR3 rules, which at your "2K" resolution has an upper limit of 200 Hz refresh using 10bits/color (HDR=ON) without compression, or at 8 bits/color, 240 hz refresh. that does not appear to be any sort of bottleneck.

Those adapters force the DisplayPort transmission speeds back to DisplayPort-HBR2 speeds that can be supported on a USB cable.

at 10 bits/color, that limits you to around 144 Hz refresh rate (with special timing). 200Hz or up to 240 are only available with Display Stream Compression, and its not completely clear that is getting turned on at the Mac, which is sending its data out on a a Much wider ThunderBolt port, so compression is not needed at the source.

at 8 bits/color (HDR=OFF), that limits you to 165 Hz refresh rate (with special timing). Higher, up to 240 are only available with Display Stream Compression, and again its not completely clear that is getting turned on at the Mac, which is sending its data out on a a Much wider ThunderBolt port, so compression is not needed at the source.

What to try next:

if you do not edit magazine cover art daily, set HDR=OFF on both displays, and re-acquire each display (such as by Sleep/Wake or Restarting your Mac.

MacOS does not work like Windoz when it comes to detecting and supplying video out to displays. It wants to detect each display independently and then send video out to each display thru a separate connection.

What I would try on the Mac Studio side of the setup. Is to run one display thru the switch and connect the second display directly to the Mac Studio using a short high speed USB-C to DisplayPort cable.

Those displays have 1 DisplayPort input and 2 HDMI inputs.

1) By-pass the switch on the Mac Studio side and run two USB-C to HDMI cables directly to the displays.

2) Dump the switch all together, run DisplayPort cables from one system and HDMI cables from the other.

see my edited response below

👍 I had a feeling, that you would chime in on this one.