I always recommend that you only convert videos if you really know what you're doing. You can actually make a video less rather than more compatible with the wrong settings.
What are the specs of the videos of you created with Handbrake? What is the video resolution and frame rate? Is it a constant frame rate or a variable frame rate?
You say you converted from iMovie -- but iMovie is not a video format. What was the format and resolution of the video you output from iMovie? Why not use it as is rather the converting it?
Thanks for the reply.
In their original form they wouldn't play video at all. They varied (either 720p or 1080p) in DV or AVI, 30fps I believe) - there's hundreds of them.
Out of handbrake they were either 720p or 1080p, H264 and in MP4 format with AAC stereo for the audio stream.
Sorry, they were cataloged in iMovie and I took the video files from the iMovie Events.localized events folder. I should mention that this was a switch from Mac to PC too. When attempting to import them directly as straight copies, they had the same symptom, except no preview in timeline either and wouldn't load up properly in Windows explorer or play.
Handbrake conversion fixed everything (fine in Windows explorer, thumbnail too now, viewable in Premiere elements timeline) but the ability to play them in preview is still broken.
Like I said, everything works great on Premiere Pro (different, also Windows PC)
As an update - copied one of the videos to a different computer (laptop) running the same version of Premiere Elements and it works! Seems there's something specific to this machine.
Intel i5-7500 3.4Ghz 6MB Cache
32GB RAM DDR3200
ATI FirePro W2100 video card
240GB Samsung SSD
4TB WD Black (Storage)
Windows 10 Pro
I disabled hardware acceleration in Edit > Preferences > General and now they play fine in preview.
I think it's because I had an onboard Intel card (as this was displayed next to the checkbox), but I use the W2100.