After Effects Stinger Export

I'm having the worst issues with AE trying to get a frame stack that works in ATEM. I have tried several methods of exporting PNG sequences and Targa sequences and none of them work. Is there a way to export these that is tried and true? I need this to work and while I could fake it with casparCG, id love for my ATEM to do what its supposed to

Anyone have any ideas? I'm using AE and exporting the files as RGB+Alpha.

Should be quite straight forward. If it's targa it must be uncompressed (not RLE) and 32bit.
What's the actual issue? Will the ATEM import it? Run it? No Alpha?

Which ATEM ? Television Studio can't do stingers .....

Do you have compatible ATEM - ATEM 1-M/E, 2-M/E, or 1-M/E Production Studio 4k?
If I am not mistaken, TGA sequences work best, and images should be 8-bits per channel with 32-bits per pixel when saving files. TGA's have two places for number of bits, but I cant recall exactly where to set that in AE - I'm normally in photoshop, and speaking from that viewpoint.
Remember you have a total of only 180 frames for clip storage. At 30 fps, that is only six seconds. This is share between both clip players, so 3 seconds each (can be modified with sliders, to 2&4 or 1&5, etc).