I have a new iphone and now GoPro Quik won’t import new media files. I’ve tried all the usual tricks – including re-intalling GoPro Quik – but still no joy
Are you getting any error message?
Also those files you're importing to Quik is it from GoPro or from your mobile phone's gallery?
Also the resolution you're importing might be to large for the software.
Please check this article: https://gopro.com/help/articles/block/hevc