Just a reference for anyone trying to create a trunk between Dell and Ubiquiti switches. In my case, I wanted to create a trunk between a Dell N2048P and a Ubiquiti Edge Switch, with a native VLAN in use across the trunk. They both seem to have the notion of Access, General, and Trunk modes. They also both suggest that General is essentially the same as Trunk mode, where tags will be retained across the link, and any untagged frames will dump into the PVID, or Native VLAN.
Unfortunately, this doesn't appear to be the case. The only way I could get it to work was to set both to Trunk, despite some suggestions out there about untagged traffic being ignored. It seems that as long as you don't set the trunk to ignore untagged traffic manually, it will act like a regular old trunk port. What's worse is that in the General mode it will sort of work.