Hi Daniel, wondering if you ever got your Premiere Pro 2020 High Sierra Mac to run the Reframe Plugin as well as being able to import Insta360 footage. I'm not able to get it to work with this combo, though I was able to get it to work on my Macbook pro running Catalina as it should. Wondering if it is a High Sierra (MacOS 10.13) problem...
I had to upgrade to Mojave, then download Premiere Pro 2019 to get the plug in, then when I upgraded to PP 2020 it worked. But Mojave slowed my computer down too much so I had to go back to High Sierra. I tried to get the plug in to show up again in Premiere Pro 2019 but it doesnt, so it appears that High Sierra is simply incompatible with the plug in.