it was working the other day but today when I try to pick a video from my local videos I get a warning saying "failed, may be 4K or shorter than 6 seconds" I have tried it on 3 devices, all have the same warning ?

Is it a 4k video that you're trying to import? If it is then you can't do that import. Get the sd card from the bird and chuck it in to your pc/mac.

As vandruten said, the GO app editor would not be able to edit 4k, only 1080p or lower.