Memory card wiped when connecting to app on iPad

My memory card was almost full, I had 45 minutes left. Made in total 10 minutes of videos. No problems at all. Few hours later I connected my camera with the app on my iPad. It sad there was nothing there. When I look at my camera directly I’ve over 6 hours of storage available.

Why was my card wiped and what can I do to unfuck this situation?

Thanks.