I just read your post with attention because also I have trouble with editing 4K with PD12.
I used PD12 since some months only and my husband bought theK video (Sony ax100) and so he tryed it and I edited 5 minutes film.
As you when play it only audio and no video!
As adviced I waited that all yellow icone above the files I download from the Sony AX100 became green.
Then could easy work on the project, add music file (download from youtube in MP3) and , add titles and decide at least to produce this 5 miuntes project. (when the icone were still yellow and so not created the shadow file when editing some files jumped, or stoped during editing)
I decided to make a file on desktop (as usual i do in order after to make by example dvd) decided to produce in MPEG4 and choose MPEG4 4096x2160, the file after around 15 minuts appear on the desktop but surprise the icone show not a picture but a music note (!?) and when I play only audio but not the video!!!????????
I tried also with MPEG4 3840x2160 and it’s the same!!!??? Can heard only the song but impossibile to see the video, the file open with quick time player, or window player have same result: only audio??!!
(Both file are for 5 minutes video 1.56GB)
So what I did wrong?????
Like you if I play the edit film created inside the library all play fine… but I need a file on desktop as I need the file to see it on computer, to make dvd blue ray, file on USB key… not so send only throught PD12 to you tube!
I also wait that the yellow icone on the produced film inside the library became green hopping that was the problem because the shadow file wasn’t created, but nothing changed on the file on the desktop, only audio, no video!!
Well I am desperate!
Hope you can help