Video mode - blank clips in timeline

I have clips with different frame rates in my timeline, 1080p 30fps and 720p 240fps.
My goal is to have clips in slow motion, so the 240fps clips were set at 1/8 playing speed.
However I noticed that the exported video seems to have dropped frames of the 240fps clips to 30fps and then slowed that instead of using the extra frames in the 240fps clip.
I tried changing the video mode but now many clips show up blank in the timeline.

How do I restore those blank clips? And how can I play the 240fps clip at 30fps without dropping frames?!

Some good slow motion discussions here:

Thank you for your help, any ideas on the blank clips issue and how to restore them?

I don’t know why the clips wold be blank. I guess you could put the video mode back to what it was before? I generally recommend that people set the video mode explicitly to what they want before they begin a project since changing the mode can cause problems to a project.

I tried setting the video mode back to the original setting both through the interface and manually through the mlt file without success. I then tried changing the values of the profile in the mlt file which resulted in different clips being blank with different values, mostly when changing the frame rate…

I have set a video mode and repeated the cuts for my edit and haven’t had any problems since.

I had that happen on a small project. White frames after export, I can’t remember what I did to cause it, but think it is because of the softwares selection of frames when compressing that has something to do with it, and probably discards the frames it thought it wasn’t going to use. I remember it was largely unrecoverable for me, too.