The Remote SL MkII units have a setting called MIDITo in their Global > Routing menu. If this is set to, for example, “M1” then MIDI messages sent to the MIDI In port should be routed to the MIDI port 1 Output. I don’t know why MIDI Note and Clock messages are passing through but Transport is not.
You should check which firmware version the DT is running as some of the MIDI settings have been problematic on old versions.