Hello Curtis, 

To mark an email with a category you will want to select the "Mark" dropdown. ( image below ) 

For the Forward filter option. I will get a feature request added for this.  

Feature Request submitted. 

Thanks !

The category list is not under the "mark" option, however if i click on "Manage Categories" I can see them there. I also just added "test" and it did not show up either under the "More" option.

Mind you this may be another bug left over from older conversions. This was originally a v14 Smarter Mail, then upgraded this January to build 8797, then recently to 9014

HI. Were you able to investigate or do i need to submit a ticket for this ?

Hello Curtis, Still can not get this to break locally, I went ahead and created a ticket for you. 

For anyone reading this, and update :

Apparently the issue for the tagging and categories is that the domain folder name on the server is in MiXeD CaSe. Changing it from HawaiianHope.org to hawaiianhope.org fixed this and a couple of other issues we were having. You have to detach the domain, rename it to lower case, then reattach the domain. problem solved.