Problems exporting footage

Hi all. I'm having some problems exporting some drone footage correctly. The footage was shot at 30FPS and I interpreted the footage to 24FPS in PP. I was trying to add a speed ramp, but when exporting, the fast part exports fine, but the slower part (which was kept at normal speed), doesn't play (just a frozen screen). I know it must be something to do with frame rates, but can't figure out what I'm doing wrong. Even when I just try to export it with no speed ramp, at normal speed, it doesn't work correctly. Screen shots attached.