@marinersway Which distro are you using?
Also, can you show all of the commands you ran to set up leading up to installing the Obsidian flatpak?
You should be able to see Obsidian listed if you have flathub configured, like so:
$ flatpak remote-info flathub md.obsidian.Obsidian
Obsidian - Markdown-based knowledge base
ID: md.obsidian.Obsidian
Ref: app/md.obsidian.Obsidian/x86_64/stable
Arch: x86_64
Branch: stable
Version: 0.9.17
License: LicenseRef-proprietary=https://obsidian.md/eula
Collection: org.flathub.Stable
Download: 91.4 MB
Installed: 223.5 MB
Runtime: org.freedesktop.Platform/x86_64/20.08
Sdk: org.freedesktop.Sdk/x86_64/20.08
Commit: d90cd8bf72dba120edefd36f2efef20368b726321c3e4a0f5573ffdb785c85c7
Parent: 76dcb0fcc6a4aa6b47052960867fdbd6a7e75af43b399bd6091874101df3c5f4
Subject: Add .ssh/ as a persistent folder (ed00e440)
Date: 2020-12-04 17:29:45 +0000