I have 2 Flynax sites, and I just noticed that one of them is working just fine with no issues.

I set my server configurations higher than John suggests:
memory_limit = 1024 MB or higher
post_max_size = 256 MB or higher
upload_max_filesize = 8MB or higher


After the test, one of my sites still does not upload images ending with upper case extension (.JPG)
All thumbnails and large images links are broken and does not appear on listing details page.

The images size was only 105 KB