I occasionally have the logging go AWOL on me, but so far doesn't happen frequently enough that I've been able to pin down the precise cause or solution (plus, when it does happen, it's usually late a night when I'm under the pump to finish off "a few simple changes, then I'm done" and have no time for troubleshooting)
The solution so far has been to reset everything. Terminate all apps and then turn the mobile device off and back on again, shut down all Windows programs and reboot the laptop, Tools Clean Project, add all the #Debugger options that look helpful, then give it another burl. I feel like one time it was resetting the router that fixed it (I use B4ABridge over wifi).
One day it will happen when I'm not under pressure, and I'll have time to try the fixes one-by-one to identify which one works, which might then give me a clue as to what causes it to happen in the first place.