HEIC - Are they supported in Elements Organizer 17?

I really appreciate all the good advice. That said, while much of it seemed helpful, I finally gave up. I also did a lot of research on the whole HEIC issue. I learned a lot, but not enough to get it to work. When I tried to import/convert the pictures, my PC kept giving the error message that the iPhone was unreachable. I also did a lot of research on this problem. Of course, if I downloaded them in HEIC form. Photoshop Elements 2019 couldn't import them. Ultimately, I gave up and paid for 2020. Having paid for 2 upgrades in 2 years, after having paid for the original version, I would no longer recommend this product. 

FWIW, I also bought a new computer last year and while that move should have been straightforward, it ended up a nightmare, but that is another long story. I ended up losing all my "people" tags.

Unhappy customer!

Let's talk about compression some more (HEIC) but I'll use music for this analogy.  I'm sure you already know that MP3 files take up much less space than uncompressed CD tracks.  That's the whole selling point of MP3 right?  MP3 files are smaller (more efficient).  As well, to take it a step further, you may also know that 160 kbps MP3's take up even less space than 192 kbps MP3's.  Why?  More compression = more efficiency.  But 160 mbps won't sound as good right?.  Think fresh squeezed orange juice vs frozen orange concentrate.  Quality vs efficiency.  Where do YOU want to draw the line with your photos?  There is no right or wrong answer to this question.  It's a values decision and none of my business.  Hope this helps.

As Phinny's link explains, you can set your iPhone to convert your HEIC images to jpeg when they are downloaded from your phone.  This has the advantage of saving storage on your phone but being able to readily use the file on your computer.  However, I have had issues when converting HEVC video to AVC using this method. 

I haven't found any good reason to use HEIC photos on my computer where I have plenty of storage space.   Opinions may differ, but an author I respect believes that the extra compression also degrades the image when compared to a jpeg.

What OS are you using?

I believe Mac supported HEIC files with Elements 2019 (version 17).   Windows support did not start until Elements 2020 (version 18).

See the Windows requirements in this article.