ABWay0
Add On to post 1....
I have just completed a study of the preview files produced in the Timeline rendering (for video and still) process in Premiere Elements 14 on Windows 10 64 bit.
The preview files formats are exactly the same as I reported for Premiere Elements 13/13.1 in the link posted in post 1. For SD, they are .avi files whether the rendered file is video or still,, and for HD, they are mpeg files with companion .xmp files whether the rendered file is video or still.
Please read the blog post for 13/13.1 which applies to 14 and which goes into great detail on the matter.
I see no evidence of a Premiere Pro preview files mixing in with those 14 preview files.
Consequently, please consider and give more details.
ATR