RESOLVED: it was caused by the app being flatpak. use Flatseal!
I have a network drive mounted to my computer (PopOS). I have read & write access to everything in the drive and can drag and drop files between two Nautilus windows, but if I try to drag a file from the network drive into an email for example, I get a popup about file permissions. Is it because flatpak apps don’t inherit my user permissions?
It’s a small thing that I think Flatpak is really missing. Drag and drop should just work, regardless of the permissions of the app, but it doesn’t because what it feels like you are doing is different from what you are really doing doing. What you are really doing is simply pointing the app to where the files are that you want it to access, so I’m unsure how to fix that problem. I would love to see it fixed though, along with an open dialog that gives temporary permission to files.
I suppose it might be doable; something could throw a pop-up that says “Flatpak app XYZ doesn’t have access to this folder. Do you want to enable access for this folder only, or all files?”