USRP2 slave PPS signal over the MIMO cable

I would like to run two USRP2’s as master and slave, and I would like to
only use a 1PPS on the master (each USRP2 would be controlled by
two separate processes). When I run the test_pps_input on the slave,
program fails. However, the master is able to find the PPS just fine.
tried a combination of running the master, then running the
the master at the same time as the slave/running the slave then the
master/etc with no luck. I think short of probing the pins on the MIMO
cable or perusing the FPGA code (which I believe is not available to the
public), I’m pretty much out of ideas.

One thought I had was that adjusting from clock_config_t::internal to
external might help, but on further review of the code, the PPS does not
appear to be affected by this. I have seen some posts about this, but
after January 20th (the most recent UHD announcement about MIMO

Thanks in advance,