There is nothing to reproduce, as its as simple as just NAV 1 radio disabling after you tune the OBS after having everything set. Using the latest ver. of MSFS.
Not sure what your specific issue is.
I can tune the nav 1 to a valid VOR freq, then turn the OBS to my desired radial, and the radio keeps working just fine! I’ve switched freqs and then gone back to the active freq and it’s fine.
Does your radio just shut down, or what?