Thumbnails are going BLACK, but only when changing the speed of the clip.
Title is the description. I could try and describe it in more detail, but I'd probably wouldn't articulate it effectively. So, here's a screen grab of the issue:
https://www.dropbox.com/s/xq52l8wgssxu887/Screen%20Recording.mov?dl=0
Anyone got any ideas? This is maddening. I'm trying to do an entire edit with 50% speed on the clips. I can't be changing the speed of EVERY. SINGLE. EDIT. OF. EVERY. SINGLE. CLIP.