You need to restart Lightroom after you've hidden the parent. I would also advise you not to use accents in the name of disks, just to be sure. So don't call it 'Fotó', but just 'Foto'. I'm sure you will still understand what the disk is for... 😉
I've tried everything, restart Lr, the Mac, etc. Didn't help. If I right click on "Volumes" and Hide the parent, nothing happens, the folder does not "promote" / get back to independent volume. 😞 (There was never a problem using the letter ó in the word: Fotó. Except an update a few month ago, but Adobe fixed that, so that is not the problem know, I have other volumes with simple letters with tha same problem)
The other problem know is, that Slideshow is soooooo slow in this catalog, I don't know why. When I start the slideshow, it builds up the preview, and that last for several more minutes, than before. I tried older catalogs, no problem.