I am using QuickTime H.264
Ah, I can't check that as I don't use QuickTime.
Are you on Windows?
Yup. But I will not install QuickTime.
When I create and save an a H.264 QT preset
using the Export Settings dialog from within Premiere,
it does not save the key frame interval or max bitrate.
However, when I create a H.264 QT preset from within
Media Encoder and save... the missing settings are saved
and can be recalled from within the Premiere Export Settings dialog.
Re-tested this a bit more, and now the kf interval & max bitrate are
being saved with the presets created in Premiere Export Settings dialog.
Odd... my first 2 tries didn't take?