Thanks for the heads up on that. I was trying to use my CCK to transfer files back to my ipad, but it didn't work until I put it in a DCIM folder. Also, I got Pinnacle Studio for iPad and I love it.I have not tried 4k.....I have a P3A, so I have no access to 4K. If the iPad won't display 4k, I'm guessing it won't allow you to import them using the CCK. You cannot view the file using the CCK before importing it to the Camera Roll.
I was only trying to be clear the CCK will only allow you to load files that look like something a camera would produce. You can't import files downloaded from somewhere unless you make them look like they came from a camera. This is a common problem. The file must have the characteristic three letters, underscore, and 4 or 5 numbers. The file name can't be DJIvideofile.mp4 as an example. The file must be inside a folder labeled DCIM on the root directory. Any variation may cause your iPad not to read it. I'm guessing you could use Handbrake to convert the file to 1080P and then it would load into your iPad. Apple may add support to 4K in future iOS releases. I'm not knowledgable on 4K.