P3421W, flickering, #5

Got good advice from Dell Support to install new firmware, M2B105. The problem is there is no way to update firmware using the same M1-based MacBook.  And M1 does not support BootCamp to boot into Windows. Parallels Desktop does not provide native access to display from VM. Now I need to find a Windows machine to try it out, will try to use my old Intel-based MacBook with BootCamp

Correct. There aren't any macOS drivers on the online P3421W drivers page. Dell only provided the firmware files that can be run in macOS. The DDM for macOS 1.50.0.041 does not list any of the P series monitors as compatible.

The Windows OS P3421W firmware M2B205 did not address flickering but should include the fixes in M2B103. It corrected the following =
1. Fix KVM bug, to enable Mouse or K/B that is attached to the Monitor to wake up a sleeping Computer which has been selected as Monitor video input source.
2. Fix PBP bug, prevent user assigning same video source to both the PBP display.

Read through the existing P3421W threads on the Apple Forum. If one is not found that helps, consider starting a new thread out there to get opinions from other Apple users.

I have tried disabling DCC and removing all the display-control software. The issue is still here, randomly come and go. When I have an issue with one of the displays in the office, I can plug another P3421W in the same port and it works fine >_<

Created a topic for apple support https://discussions.apple.com/thread/253562684

Hi @andrey leskov any success yet?

I received this monitor on Friday and I'm seeing the same behaviour,  intermittently the display starts wavering.  I get this on both my windows laptop and macbook m1.  Updated the firmware, but no improvement. 

@dhendry1 Unfortunately no, nobody knows what is the issue. Now it seems a classic "not my business" situation - Dell says P3421W is not officially supported for Mac, Apple forum says "What PC users call "display drivers" are no more than a settings file for a specific display." Btw, Bootcamp killed my old Mac OS and I need to reset, format, and reinstall everything. This issue is taking too much time of my time, so I gave up and now thinking about changing monitors if the issue will affect our employees and there will be more complaints, not just me. 

Thanks for the info @andrey leskov.. Out of interest did you try using USB C to DisplayPort? Not ideal, but I have read elsewhere that this can help - I haven't tried this myself yet.

I believe the issue is in the display itself, not the cable. At least in my case. I use the original USB-C to USB-C cable coming with the display. 

Please check videos with glitches. Sorry for the background music and open windows, I leave everything authentic: 

1) Strange stripes and flickering in MacOS UI

2) Same stripes in display menu with no signal cable (I'm plugging off my USB-C during the video)

Video 2) makes me believe the issue is in the display. 

Oh wow, your issue is very different to mine.. agree your monitor looks faulty.

I have a slight flicker on the left side of the panel, however works fine when connected to a Windows laptop, so its related to Macbook M1 compatibility. 

Found a similar to mine screenshot at reddit https://www.reddit.com/r/MacOS/comments/sgekpz/how_do_i_fix_this_one_of_two_monitors_i_am_using/

@andrey leskov do you still have the issue or have you found a solution on this?