I also had issues in the past using Discover for Flatpak I ended up just using the terminal from then on. I also just tried updating my flatpaks on Artix just now and didn't run into an issue.

Do the updates fail or do they just take a while? I know Fedora had an issue a while back with them using their own repos over flathubs offical ones.

You can see how to get the official repo here

I've been having the same issues with an arch-derived distro and it also gets stuck, leading me to believe that the issue's on flatpack's distribution end.

(I use shelly for my updating, and it works fine for pacman and AURs, but at least for the past day it's hung up on flatpacks. I also tried running "flatpack update" in bash with no results.)

Because of that I don't think there's any solution other than manual installation until Flatpack solves the distribution issue.