Giant Instinct Barbarian
 

Is there any way to have the correct rage damage show up?

If you aren't seeing what you expect, raise a bug report with the reporting tool within HLO.

Giant instinct requires you to have a larger than normal weapon to activate the extra, so I didn't know if I was just missing where to set that.

Do you have an oversized weapon equipped when you activate rage? It only increases the damage if it finds one actively equipped to your character. Hopefully it's just something like that, though regardless I may look into how that is set up in order to increase clarity.

That's what I figured I just can't seem to find where to set a weapon as oversized.

When you purchase a weapon, it should be on the right, there's a drop down menu.