Once upon a time, I used to be able to automatically import into PSE the photos that appeared in the OS X iPhoto folder. For several versions of PSE, that functionality has been lost. The majority of the photos I take end up there, and exporting them and then importing them into PSE Organizer has been so tedious that I have, for all practical purposes, stopped using PSE. I'd love to get back to it, but I've given up on upgrading it past 2015 because the needed functionality has not been restored.
By reading product descriptions on Adobe.com, I cannot tell if PSE 2020 has regained the ability to "watch" the Photos library in macOS. Any enlightenment appreciated.
It’s generally best to avoid referencing the same files in both Organizer and the Apple Photos app. Otherwise the Library could become corrupted. Apple now offers the use of extensions meaning you could edit directly from Photos in the Elements Editor app and save back to Photos. See if my blog post helps.
I understand the problem, but it's disappointing that, given the time since El Capitan, Apple and Adobe haven't corrected this problem. I have so many years of photos in PSE Organizer, that I'm not about to switch to Photos. Perhaps there's a way to have any photo added to Photos automatically exported to a plain folder which PSE Organizer can "watch."
You can create a separate folder and mark it as a watched folder. You can then export into that new folder from Photos; either as unmodified originals or with edits already done in Photos. I’m not aware of any automatic export process in Photos so it’s something you would need to do manually.