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User profile for user: Hotch3f
Hotch3f Author
User level: Level 1
10 points

mp4, m4v missing thumbnails OS Monterey

Since upgrading to Monterey my mp4, m4v files are missing their thumbnails.

I have many movies that i used Subler to add a cover photo and these all worked before and were visible in Big Sur

i have tried the removal of com.apple.finder.plist and forced finder to relunvh and this does not work.

Here lies the problem.

If i reboot the iMac the folders all show the thumbnails correctly, but if i leave the computer for a few hours and return and wake it from sleep the thumbnails are all gone.

if i transfer a mp4 from something like my GoPro the thumbnail does not even show the preview in the thumbnail. just a generic white thumbnail. But again if i reboot it is fixed, but once the computer is woken from sleep they are again gone!! This only happens after a few hours of sleep and not if i let it sleep and wake the mac after a few minutes.

Can anyone help

Posted on Nov 2, 2021 2:51 AM

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User profile for user: Hotch3f
Hotch3f Author
User level: Level 1
10 points

Posted on Nov 4, 2021 1:14 AM

After days of trying to sort this out i did a clean install of OS Monterey over the top of my exisiting OS. 24 hours later and everything seems to be fixed. woke the computer after a long sleep and all the thumbnails are still there!!!

There must have been a glitch in the Matrix.

Thanks to everyone that responded

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User profile for user: Hotch3f
Hotch3f Author
User level: Level 1
10 points

Nov 4, 2021 1:14 AM in response to Hotch3f

After days of trying to sort this out i did a clean install of OS Monterey over the top of my exisiting OS. 24 hours later and everything seems to be fixed. woke the computer after a long sleep and all the thumbnails are still there!!!

There must have been a glitch in the Matrix.

Thanks to everyone that responded

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User profile for user: Jeff_W.
Jeff_W.
User level: Community Specialist

Nov 3, 2021 6:34 AM in response to Hotch3f

Hello Hotch3f,


Thanks for reaching out in Apple Support Communities! We understand you're having trouble with your thumbnails since updating to Monterey. We're happy to assist you with this.


Let's start by testing in safe mode. This can help bypass software that can cause conflicts:

How to use safe mode on your Mac - Apple Support

Where are the files located on the Mac? For example, are they located in a folder or iTunes?

Does this occur in any other user accounts?

Does this occur on the files that you didn't use Subler with?

These details can help us isolate the cause of the issue.

Best regards.


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User profile for user: jdo_apple
jdo_apple
User level: Community Specialist

Nov 3, 2021 7:44 AM in response to Hotch3f

Hi Hotch3f,


Thanks for the update. We recommend ejecting and disconnecting the external drives and test to see if the same thing happens with the files on the Mac. If so, run disk utility on your hard drive: How to repair a Mac disk with Disk Utility

Next, connect the external drives back and run disk utility on them. If the issue persists, Contact Apple for support and service.


Have a wonderful day.

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User profile for user: Hotch3f
Hotch3f Author
User level: Level 1
10 points

Nov 3, 2021 7:04 AM in response to Jeff_W.

When i boot into safe mode the thumbnails are restored. I knew this would happen as when i reboot my iMac the thumbnails return. The problem occurs after a few hours of sleep time on my iMac. The iMac is always on as it is the media library for all my Apple TV's.

The files are located in folders some on the iMac and some on external hard drives (both of which have the same problem)

I don't have any other user accounts on the computer as it is only myself that uses it

This occurs in files that i have not used Subler for ( like transfering mp4 from my GoPro)

also i have now noticed that is also affecting .jpg files and .nef files ( i am a photographer as well) these now do not show any previews.

The problem always fixes itself after a reboot but after several hours it goes back to no preview in the thumbnails

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User profile for user: NormanUK
NormanUK
User level: Level 1
14 points

Nov 5, 2021 3:32 PM in response to Hotch3f

I am having the same problem on my iMac and have been searching for a solution for a few days now.


Like you, I also loaded a clean install over my existing one and for a few hours it looked as though I had solved the problem but soon the JPEG, PDF, MP3 and M4V previews were all missing again.


I have now deleted 3 seperate times the preference file com.apple.finder.plist from the library which was a suggested solution on some websites - but it doesn't help.


A shut down, re-boot and a re-set of the NVRAM worked once, but after an hour or so the preview icons reverted to generic icons again.


Interestingly, my MacBook Pro which I updated to Monterey on the same day has none of these issues and yet 95% of the programs, files and set-up are exactly the same on both laptop and desktop.


As I edit a lot of photos on my iMac, this is becoming very very frustrating.


Any users who have other suggested solutions would be much appreciated.

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mp4, m4v missing thumbnails OS Monterey

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