If you dare to use a terminal window, try this:
chmod -R 777 /Users/drcasmithimac/Documents/Obsidian/
Don’t know if it helps, but then you at least have read-write permissions for for any process/user.
Disk Utility also tries to fix known permission issues and set back the right flags, that might clean up the home Documents folder permissions.
Also check Preferences-Security-And-Privacy-Files and Folders and make sure Obsidian is there, if not add it in.