MPC crashes when auto changing framerate in fullscreen

I'm using MPC-HC (64-bit) Version 2.3.4.29 on Windows 10 (64-bit).
The problem actually started at least one, maybe two updates ago.

I use MPC with madVR on my home theater projector.
I have my settings set to auto adjust framerate when going into fullscreen.
It's always worked great, but after one of the recent updates within the last couple months, now when I go into fullscreen, the projector framerate changes as it should, but the video will freeze with the elapsed time in the progress bar still progressing.
I have to force close MPC from task manager and I get the error message: "timeout when closing filter graph".

If I go into advanced settings, and turn on FullscreenSeparateControls, everything works great.
But if I run the interface from the fullscreen monitor, it crashes again.

I have performed the following troubleshooting steps:
I have verified that all settings in MPC and madVR are still correct.
I updated to the most recent version hoping it would fix it, but unfortunately the problem remains.
I updated Windows, but this too did not resolve the issue.
Lastly, I updated my graphics card drivers, but still, no success.

The only thing I have not done is downgrade MPC to a previous version.

If anyone has any advice on this, I appreciate your help.

Steve

Which hardware decoder is selected in LAV Video Decoder?

If you use D3D11, then you should explicitly select the GPU device. This forces it into copyback mode. Madvr has freezing issues when using D3D11 native mode.

Thanks for your reply, Hardware decoder is currently set to: None.
So I tried D3D11 selecting my GPU, but unfortunately that did not fix it.
I then tried the different hardware decoders but still nothing.
I also tried enabling and disabling D3D11 in madVR, but no luck.

I seem to remember having issues with the hardware decoder in the past and setting it to None was the only setting that worked. Unfortunately, that is no longer working.

Any other ideas?

None is fine and has least chance of issues.

Are you using the MPC-HC fullscreen settings to switch display mode, or Madvr? It is best to let Madvr do it. Certainly when it also need to toggle on HDR.

If FullscreenSeparateControls option really has an effect on the problem, then you could try some older builds. You can get (development) builds here:
https://github.com/clsid2/mpc-hc/releases

Does it make any difference if you use F11 to switch to fullscreen instead of double-clicking video?

Also, if you have changed any of the queue sizes in Madvr settings, then try setting them back to defaults.

So F11 made no difference and the madVR queue was still at the defaults of 12/8.
But I found something interesting.
I recently added a new display bringing my total to 4.
I noticed that when I go fullscreen and the projector blanks out for a second while changing the framerate, my recently added display was also blanking out. The other two were not.
So, I unplugged that display and tried again and guess what, it worked!

So for whatever reason, the new display is trying to change framerate along with the projector.
The new display does not support multiple refresh rates. So I think we found the problem.
But I have no idea why they would be linked like that.

I assumed it was a recent update because I've only had the new display for a couple months and it never occurred to me that adding a display would cause this.
So, it was not an MPC update after all.

Have you heard of anything like this before?

Here both monitors go blank as well when switching mode of second monitor. That by itself shouldn't be a problem.

Have a look at the device list in Madvr settings. Do you see any duplicates there? If so, that is a bug in Madvr. Happens rarely on Win10, or more often on Win11. Workaround for that is to use a beta version of Madvr.

But first try deleting any old/invalid/duplicate devices.

Also test if you can manually change the mode of the projector in your graphics card settings when all 4 are connected.

No duplicates in madVR.
Yes, I can change the mode of the projector from my graphics card settings.
Nothing seems to make a difference.
The only thing that seems to work is disconnecting the newest display from windows display settings.
So I'll do that as a workaround for now.
Still seems strange that adding a monitor would cause an issue like that.
My primary 2 displays are 4k and the projector and the new display are 1080p.
Not sure if that matters or not.

But thank you for your suggestions. I do appreciate your help.
Steve