Now using AL 1.9.2.16 on windows 7 32-bit OS, NTFS file system.
I am experienced user of AL for many years, so I know about the basic operations.
I create category, and add my HUGE collection of Poser content to the category.
But.
AL does not want to add some of the folders after synchronisation.
I create a new category, and add those dropped folders.
I run a synchronisation, and AL accepts those folders in the new category.
I think there is some type of cap or maximum number of items for each category.
Anyway, this is my work-around, in case anyone needs to know.