problems exporting with transparency and quicktime display

[Ilenia5EC1]

hi everyone, I have a mac with Big Sur operating system version 11.2.3.
I have always used after effects to make animations. For some time, during video export, I can no longer get transparency while adding the alpha channel.

these are my steps:

          file > export > add to Render Queue > format Quicktime > channels RGB + Alpha.

in this way, up to 3 months ago, I am always successful on this same device.  Now, once exported, it tells me that the file is not compatible with quicktime player. 

is there a problem with quick time? it does not open any files to me.

using another solution, trying not to export with .mov, I tried with media encoder.
these are my steps:

         file > export > add to Media Encoder Queue > format: H.264 > render alpha channel only.

the result is a video with a black background and white animation.

obviously, in the composition, the transparency is set which is displayed correctly while editing the animation.

I have already tried to uninstall the program and reinstall it.

how should i do? Help.

[Rick Gerard]

What format are you using? Video with Alpha will display with a black background in media players like QuickTime and Windows Media Player. The Animation format is deprecated, it is only 8-bit, and should not be used. Perez 444 and DNxHR/DNxHD support alpha channels and they can be rendered at higher bit depth which improves the quality of the alpha edges a great deal. GoPro Cineform also supports 10-bit and Alpha channels but the current builds of Premiere Pro can't use the format. It used to be my default format for DI (Digital intermediates) but I've gone back to ProRez 444 as the default.

H.264 files do not support transparency. The alpha-only file you rendered is supposed to be used as a Luma Matte (track matte) in an app that supports track mattes or setting mattes from other layers like After Effects and Premiere Pro. 

[vicky5CD7]

I'm also running into this issue... I've used the new track matte feature to move logos from behind a line, like a lot of the template/generic lower third graphics out there. Looks great, go to export, andddd nothing; not transparent, but a black background in QuickTime - if I'm even able to open the file ("not compatible"). 

1. File > Export > Add to Render Queue
(leave the Render Settings on Best Settings) 
2. Change the Output Module > Lossless with Alpha 
3. Open the adv settings for Lossless with Alpha > Change codec to ProRes 4444

*Additionally, I've tried changing the Video Output Color from Preformatted to Straight (unmatted) and upping the output bit rate to 32, neither producing a better outcome.

- Am I missing something settings-wise on how to properly export a "transparent video"?
- And/Or what programs are we using following the creation/export of a transparent animation, if we can no longer use QuickTime? Or other media players? 

So confused... I see lots of tutorials on the track matte feature, but can't seem to get it out of AE (in a useable format). How are yall doing it? 

I had to blur out the content (but you can see it's transparent in AE), but I've attached a few images to show my settings.

[vicky5CD7]

Ah - forgot to include that I'm running Mac OS Sonoma 14.3.1. 

[Kaijukilluh2099]

Welcome to the club, bub! I'm in the same spot and of course there's no helpful solution I can find.