Welcome in the forum!
Can you please post your complete project, so that we all can have a look at all of your settings. To do so, use
Creator->File->Create Workspace Bundle (minimal)
and attach the resulting file.
Thanks. I think I actually figured it out on my own after playing around for a bit. It looks like I need to configure the transfer for 32 bits, and then the top 24 bits get dropped. Weird, but I guess that's how it works when dma-ing directly into gpio registers?
Sample code is attached if anyone wants to take a look or has any thoughts.