When I look at my tuner info, it doesn't say anything about DMS or BDA. Is there a setting on the tuner itself that isn't showing the hardware correctly in MC? Or is there a setting in MC that I missed when I upgraded to the HDHR Flex 4K as my tuner?
Sorry about the confusion. When we initially developed TV tuner support over 20 years ago, there were analog OTA and analog Cable channels. The tuners were Analog Tuners. Shortly after that we started having digital TV. These were supported on Windows only, using Microsoft bda architecture. These tuners are called "digital" tuners in MC. In MC setup, they are under "Antenna (over the air)" service type. ATSC devices are originally bda only. The DVB devices used in other countries are similar in that they are supported as bda devices.
Some of these tuners are network devices and support network protocols, giving us the ability to support them in Mac and Linux. These are under the service type of "Streaming (from a network tuner or from the Internet)". DMS stands for Digital Media Server, and is available with one of these network devices.
For ATSC 3.0, it appears that bda is just not updated to handle the new format. Thus we rely on devices such as HDHomeRun to do the tuning and we just get the stream from the device via DMS.
In television setup, choose "Streaming (from a network tuner or from the Internet)" for Service type, and choose "Tuner Stream" for Tuner type. Tuner Stream is just another way of saying "DMS". Sorry for all these confusing terms.
From there you should be able to complete the setup by following the wizard.