iPhone 12 Pro videos won't import into Premiere Elements 2020

"From what I've read ....."

That may be true.  I have no way of knowing.   My reading suggests that the licensing of the HEVC/H.265 codec has been complicated, convoluted and confusing.  So even if they are the same, who gets paid and how they get paid is not.  It may have been a year or two ago that I first heard of H.265.  It was supposed to take over making everything relating to video faster and better.  The tangled licensing procedures slowed it down to the point that we may see someone else provide a better, faster, more compact codec.   

My personal fix is to avoid it where I can.  H.265 does not make my videos better than the universal H.264.  

"I have the HEVC Video Extensions from Device Manufacturer installed (by Microsoft)."

That's the problem.  That codec is intended for builders of computers.  You are a consumber and Microsoft wants you to buy the $.99 version of the codec.   It may be a challenge to get rid of the free one and install the $.99 one.  Consider getting help from Adobe techs by picking Online Support in the Help menu.

Did you see this?

https://community.adobe.com/t5/premiere-elements/faq-what-should-i-do-if-premiere-elements-2020-fails-to-import-hevc-media-files-in-windows-10/td-p/10953097?page=1