I built a pretty large aircraft, and put a drop probe in its cargo bay. Basically a relay station, with lots of battery, solar panels, 6 antennae (4 relay, 2 shorter range), and some atmospheric science. I flew the plane to where I wanted to drop the probe, and deployed it. It deployed landed just fine (I switched to the probe just after release). After it landed I switched back to the carrier plane to fly back home. So far so good, but when I tried to go back to the probe, it didn't exist any more! Should I have left the plane unrecovered before going back to activate the science and configure the antennae?
I'm using KSP 1.3.1.1891, with a bunch of mods. I doubt that it was a mod issue. I didn't quit the game or anything like that, and didn't accidentally revert the flight or anything. I _did_ recover vessel before I tried to go back to the landed probe.