I believe you need to include the comma between the main search term and the exclusions, although it doesn't really state that in the Admin Guide.
For example. using your above example, try the search like this:
DRE,-MacPro*
When using the above type of syntax I was able to successfully search for Macs in the JSS that started with a certain naming convention, but excluded any that also had the term enclosed with the asterisks.
Edit: Just wanted to add that the full Admin Guide is either incorrect, or there is a bug in Casper Suite 9.0. The specific application search example of using the exclusion clearly does not work, just as @chris.kemp stated. I actually copied and pasted the exact example of "Microsoft -Word" into Application search and I get 0 results. The only way I can get it to work is by using the following:
Microsoft, -Word*
The Admin Guide needs to be updated or the issue needs to be fixed in a future update if it was intended to work the way its outlined in the guide.