Took me a while to figure out that Signal can't save outside of Downloads as well, especially since its not the default dir it opens when trying to save an file. There's no feedback of any kind.
I see flatpak more as a distro independent package format than a way to secure my system.
Exactly, the lack of feedback is the worst part of this. The way it's done right now it looks like the file picker is completely broken and riddled with bugs; the user goes in expecting it to behave normally(given that it looks exactly the same) but it won't show files in the home dir, refuses to even show user-created directories etc.
Even a horrible and annoying pop-up dialog saying something like "file access error" would be better, at least it would be easier to google.
More confusing one is that flatpaks can't access mount points inside your home directory even with the correct flatpak permissions set.
Assume that you are running Steam as a flatpak and you want to add an extra drive to store your Steam library on and you have your extra drive already automounted inside your home directory and the correct flatpak permissions set, Steam will not find it anyway.
You have to use a mount point outside of your home directory to get that to work.
I see flatpak more as a distro independent package format than a way to secure my system.