GoPro footage imports OK, but only drops into audio track

Hi all.  Really hoping someone can help.  I've imported some GoPro .MP4 footage, and it's showing up in the media browser as an audio track.  Double clicking the file allows me to scrub through and apply effects, however it won't allow me to drop it into the sequence other than onto a Audio track.

The file properties are:

Type: MPEG Movie

File Size: 59.62 MB

Image Size: 1920 x 1080

Frame Rate: 59.94

Source Audio Format: 48000 Hz - compressed - Stereo

Project Audio Format: 48000 Hz - 32 bit floating point - Stereo

Total Duration: 00:00:16:31

Pixel Aspect Ratio: 1.0

Video Codec Type: MP4/MOV H.264 4:2:0  (Full Range)

Is there anything obvious that may cause this to happen?  I have a mix of footage shot at 1080p / 4k / etc @17278815/60 FPS, from GoPro, DJI Mavic all work fine, but for some reason a few videos just don't want to play nice.

Are there any project settings that would disallow certain videos being imported?

Thanks : )

Mick