Is this a bug? I have configured a path to a folder containing attachments, the name of which begins with a dot. After that, I am unable to add attachments to my notes. If I change the name of the attachments folder so that it does not begin with a dot, adding attachments begins working again.
Other than the <vault>/.obsidian/ settings folder, I don’t think Obsidian recognizes hidden folders.
Have a look in Feature requests. There may be something there.