Try this as it works here with midi and RTs:
C.dpgs,C/G C.dpgs,C/G

As I said it works however you may not like the four on the floor chords that it plays.

The only other way I know to do this is with two passes through a sequencer. Pass one save the song without a bass line. Pass two change the bass line to something like I described above but only save the bass line. Merge the two saved parts in your sequencer.

Good luck.

My momma didn't raise a fool. And if she did it, was one of my brothers.

64 bit Win 10 Pro, the latest BiaB/RB, Roland Octa-Capture audio interface, a ton of software/hardware