If you have a Tagbox/Category "2000 - 2010" and then type this in as a search term or select the search suggestions then the assets in this category will not be found by the simple search. 

The minus is a search operator in Picturepark. When there is a space in front of it the search interprets this as you wanting all assets tagged with 2000 but not 2010 so anything tagged with 2000 - 2010 will not be found.

You do have several other possibilities:

Not use any spaces e.g 2000-2010 - I would recommend this option.

Using the space only after the hyphen e.g. 2000- 2010

Use EN-dash (Alt + 0150 Windows)

Use EM-dash (Alt + 0151 Windows)

While a space between the hyphen and the year may look better - technically in English spaces are not used when using hyphens: https://jakubmarian.com/hyphen-minus-en-dash-and-em-dash-difference-and-usage-in-english/.