I have tried the obsidian package, and the obsidian-appimage package from the AUR. The start up message is the same:
Loading main app package /usr/lib/obsidian/obsidian.asar
No protocol specified
The futex facility returned an unexpected error code.
Aborted (core dumped)
The issue isn’t with the installation it seems to be a config or runtime error. Both these packages in the aur simply download either the source from github, or the appimage from the link you provided.
Any help in getting more verbose info would be appreciated. Closing this isn’t going to solve the issue and other people will open new tickets…