I use my fleet of Echos to control much of my home automation and the voice recognition success rate has gone way up compared to a year ago.  Within the last few weeks, though, I'm starting to get some weird error messages despite the commands doing exactly what they're supposed to.  When I issue a command, the light ring spins for a bit, whatever activity I asked for starts, the light ring spins a bit more, and I get a "Sorry, xxx is not responding" or (this morning) "Sorry, I can't find a devi