Too many synchronized folders

Yesterday I had updated my external HDD (from another HDD, I use two HDD - one at home, one at office and regularly synchronize them) where all the audio files are stored.
Then I saw that Audirvana did not synchronize the HDD, but all single folders - so I had a lot of folders and you can only delete one after one (I found no way to mark all and then delete all).
I have no glue how this happened, but I strongly suggest to offer a way to mark all folders!!!

Furthermore my DAC was no more connected. I assume this is related to the many folders…
Newest Audirvana version installed.