Thumbnails and preview icons not being generated in Catalina 10.15.7

Thanks for taking the time to reply, toastosxDC. The problem here is actually the opposite: this type of 10-bit video file is brand new (the GH5 was introduced in late 2019) and apparently the Mac Finder/QuickLook still does not support it in terms of generating a thumbnail preview. I figured this out because certain files shot with the same camera actually displayed thumbnails, but those shot in 10-bit 4K did not. In any case, the workaround I came up with is pretty simple. I now use EditReady software to generate thumbnails for the 10-bit files within the EditReady app. It's not as convenient as having Finder thumbnails, but it let me preview hundreds of video clips relatively quickly and efficiently. As for the older formats, that's a bummer. In any case, thanks again for your reply.