The last two projects, I've had some unusable artifacts when using optical flow. It's not the "normal" artifacts that you sometimes get with optical flow; these are bright blue little boxes that are showing up on the "created frames." Here's a photo:
If it were just one frame, I could try to keyframe a fix, but it's probably 25% of ALL the "created" frames. I've had to just bump these clips to AE to accomplish what I usually do natively in Premiere. It's happened on multiple projects, and the footage that's giving me this problem is Canon 5D MKIII. If it's important, I'm using a brand new 10-core iMac Pro.