KVM Model:
1.4 Display Port KVM Switch - Dual Monitor - Two Computer (SQ1007387)
USB Interface (5-gigabit or 10-gigbit):
10
Problem:
When swapping from Windows PC to M5 Pro MacBook Pro, the monitors aren’t recognized until the Moshi USB-C-to-DP cables are physically unplugged/replugged into the MacBook.
Other Notes:
This setup worked consistently with an M1 Pro MacBook Pro - I’m certain it’s related to the new work computer, but I’m not sure about how to fix it. I’ve considered ordering new USB-C-to-DP cables?
Sounds like a sleep-related setting. The Mac forums have a lot of posts regarding that. Also make sure your USBs can wake your Mac
I’ve made sure to enable the Prevent automatic sleeping on power adapter when the display is off, which I think is the sleep-related setting. However, this happens without my MacBook going to sleep; if I hit the button on my KVM to swap machines, then immediately press it to go back to the MacBook, I have to disconnect and reconnect the Moshi USB-C-to-DP cables. All of my other USB peripherals work immediately (going through the KVM) except for the displays. 
Oh ok so that sounds like an EDID/monitor emulation-related issue.
You might try something like Better Display. I had someone report that fixed their issue with EDID on Mac
Welp, finally got around to giving it a shot using BetterDisplay - I tried pulling the EDID from the monitor and various detection settings in there, but BetterDisplay showed that the monitors were disconnected when I swapped via KVM. Is there a newer cable recommendation than the Moshis from ~2022? Should I look into a repeater?
You can use a repeater to physically implement it, but it should be possible with better display.
Create a Virtual Screen
Click the BetterDisplay menu bar icon → Settings → Dummy Displays → Create New Dummy
Match this dummy to your monitor’s native aspect ratio (e.g., 16:9)
Configure Mirroring
Open your Mac’s System Settings → Displays. Set your actual physical KVM-connected monitor to mirror the new virtual dummy display. Then, just make sure the dummy is set as the “Main Display.”
Sleep setting
In the BetterDisplay settings under your Dummy display options, locate the setting for “Disconnect Behavior.” This should be set to “Ignore display disconnection.”
Let me know if this works for you.
I might just have to order a physical repeater or something; BetterDisplay with Virtual Screens makes the monitors “flash” when on dark backgrounds, makes the refresh rate unstable, and doesn’t actually solve the issue. My MacBook legitimately does not detect the monitors until they’re disconnected and reconnected physically 
Huh yeah not a problem I do do think EDID feeders would fix this issue.
What monitor resolution and refresh rate do you have? Our DisplayPort EDID feeder is limited to 1.2 (4K 60Hz) atm.
1x 1920x1080 @ 240Hz, 1x 3440x1440 @ 165hz
Additional things I’ve tried today:
- Updated to latest MacOS
- This was interesting - I swapped to my PC while my MacBook was updating, and on the first swap, it worked correctly, and both monitors were recognized. I swapped back to PC, then back to MBP, and the displays were never regained without replugging.
- With dead connections, tried power-cycling the monitors.
- With dead connections, tried power-cycling the KVM.
- My PC is on PC 1, which the KVM restarted to, and, upon switching to PC 2 (MBP)… nothing.
- Tried swapping with 1 monitor connected to MBP at a time
- Tried swapping with MBP closed.
- Swapped PC to PC 2, MBP to PC 1.
- Nothing, even after power-cycling KVM.
Next steps I’m trying: I may as well try a dock, I guess? I bought a Plugable TBT4-UDZ, just to see if it would help at all. I don’t have tremendous hope for it, but maybe? If that doesn’t work, I’ll order whatever @Level1_Amber recommends from the L1T store (Feeder? Repeater?) and try that? I also ordered a variety of new/different USB-C-to-DP cables to test, not that I expect anything to matter there since I’m already using Moshi cables.
cc @wendell in case you have any other ideas?
hmm, if it worked on the first swap, thats interesting.
try unplugging all your monitors from power and dp for about… 5 mins?
see if that makes a difference
Negative Ghost Rider, no change on the longer power cycle.
HOWEVER! Unfortunately for me, and fortunately for the bottom line of Plugable, using their TBT4-UDZ dock, the most expensive potential solution, seems to have resolved my issues, at least in a 5 minute test. Sorta wondering if there’s something strange with the handshake between the M5 Pro/Tahoe 26.5.x MBPs and monitors using USB C out to DP?
Whatevs, it’s working for now, I’ll come back if there are any issues.
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I used to have some loaner visiontek thunder bolt to 1/2 display adapters (hdmi and dp) and those were great for diagnosing handshake issues, too. Sadly they’ve all disappeared.. they were pretty cheap and fixed handshake issues often, too. did you try all the usbc ports on the m5? we had one case once where Just The One usbc port on an m4 was troublesome.
Yeah, I did. It only has 3 ports (frustrating), but every combination I tried failed in the same way.