Assigning Multiple Categories

[Aubrey]

I have a number of unassigned files, in which there are no categories.
Many files have multiple categories, for example family members in photo, location of where photo was taken etc.

Whenever I click on first category the file then disappears from my unassigned files list, this is before I can addon extra categories.

I've looked in the preferences but cannot find where to override this.

Thanks,
Aubrey.

[Mario]

The idea behind this category is to show you all files not assigned to any category. As soon as a file is assigned to a category it no longer belongs @Unassigned and is removed. Otherwise IMatch would display false data. This automatic update cannot be disabled.

You should not actually 'work' in the Unassigned category. This makes your life unnecessarily hard. 
Why don't you just <Ctrl>+<A> to select all files in Unassigned and add them to another (temporary) category?

Tip: Right click a selected file and select the "Create category from selection" command to bring all selected files into a new category.

When you are done with assigning a file to all categories, press <U> to remove the file from the temporary category.

Or, add all selected files to a flag, bookmark, dot or pin collection. Then assign categories from the Collection View.

[Aubrey]

Mario,
Thanks, this is a good idea.
IMatch 3.6 allowed workflow I described - I need to get used to the new paradigm.

Aubrey.

[andrewh]

I assign a category "NOT assigned" on import of all files then work just as you do in 3.6 - make all the assignments then remove "NOT assigned" when I am happy.