Side note: Linux platforms work differently than Windows when it comes to tracking changes in the file system. That includes many, or even most, NAS systems such as QNAP, Synology etc.
Linux relies on a table in kernel memory which keeps tab on where changes are made in the file system. The size of that table (i.e. the assigned RAM area) defines how many folders can be tracked.
Sometimes this designated RAM can get too small if a lot of folders are added.
See: Linux Tips - #9 by ChuckPa
