@soundtraxx I believe the error did start with 3.3.6, but it didn't become apparent until I added a new event. I did manage to get my events back by changing the categories, but I needed to add a new event and it went down again. I have been unable to fix it. Thanks for the tip about 3.3.1, I am going to try this.
To make this a quicker fix, I created a new 3.3.1 site with only the shell of my template installed and DT Register.
I'm using my regular website for all aspects, but for the registrations it links to a temporary joomla installation I named /build/. Then I created my menu items as external links to my original 3.3.6 website, but all registrations are processed on the temporary 3.3.1 installation.
That way I didn't have to rebuild my entire site, I just have two joomla installations, with 1 only used for DTRegister until Nathan fixes this.
The following user(s) said Thank You: ZeilraceRally