[Steve Ogden]

…I cannot believe I didn’t know that one! ….Thank you Cassius!

[Steve Ogden]

OOOH! Yeah, that’s a doozy of a bug. Thank you!!! – I spent all morning troubleshooting failed renders.
And sure enough removed the Median effect and it worked fine.
I’m adding a note to this thread, that when rendering it in media encoder I would get the message:
“Encoding Failed ———- The Operation was interrupted by user”
(which I did not)
Though when rendering it in AE I got the Photoshop Library Operation failed message.
I’m having this problem in AE 2019 16.1.1 – so it’s pretty lame that hasn’t been fixed. I’ll submit a bug report.

PS: Depending on what you’re using media for, a fast blur, then a levels, clamping the alpha channel works

imac 27″ on Mojave, AE 16.1.1 and ME 13.1.something