The old frame export was simple. The newest update doesn't even let me change the file name. It doesn't let me export with a transparent background anymore when exporting masks.
In the new export frame options to get what was there before simply select
channels:RGBA (A = alpha)
The old feature was always PNG and always output alpha.
Alright, what about file name changes? Can't seem to find ways to change em.
At the moment, you can't change the file name.
There's a feature request thread. Go "Vote Up!"
Otherwise, as Norman said, for Alpha (transparency) PNG, TIF, TGA and, EXR all support alpha. Just make sure "Channels" is set to RGBA
Or you know... rename the files via your actual operating system after the fact.
@spyresca that does work, but if, for example, I've exported a file and brought it to Timeline/Media Bin, then gone out of Hitfilm to rename the file, on returning to HF I have to relink the rename, AND manually rename in the Media Bin (and Comp Shot layer, if applicable).
So, yeah, it's doable, but certainly nicer, faster, easier if one could just rename the files at Export. Go Vote Up the feature request thread linked above, por favor! 😁