Bug in 3.8.21

Within an hour of powering on, I experienced the following problem:
SmartSDR suddenly vanished with an error message stating that the connection had been lost. A new selection dialog appears and says no radios available. About 10 or 20 seconds later, SmartSDR reappears and begins working normally with one exception. I'm not exactly sure what its proper name is - the floating window at the top of the slice. I had two active slices. However, the bottom slice came back with no floating control window. I can't find a way to get it back. Note that I did not have this problem with an earlier version. Closing the slice and then clicking on +RX gets "Slice limit has been reached...". There is only one active slice visible. Clicking the button in the lower left with the waveform graphic and+ restores the slice but still without the floating control window. I wasn't able to find anything in the manual that explains how to get that control window back. Shutting down SmartSDR and restarting returned to the same state with no control window in the bottom slice. Not sure where to go from here. Also, my network is rock solid and the radio shares the same hub as the computer with 5 green bars in the lower right.