+ AA6YQ comments below
I think I had a disconnect from Commander while using WSJT-X. I went to transmit and it would not. I then hit Tune on WSJT-X and after a brief hesitation, it started to transmit.
+ Yes, that's the sort of behavior I've seen with both SmartSDR v2.5.1 and v3.0.27. I did not see it with v2.5.0 or v3.0.25.