ESP8266-RaspberryPi suddenly only one way communication

My Pi server ( 0.28.0.0) has been running for months with multiple ESP8266 devices. Suddenly they won’t accept simple on/off commands from blynk app (android 2.16.6) but the devices continue to send to blynk app. It is one way only. Did something change?
Thanks.

Hello. Please update to latest app version.

Thanks, that fixed it, except that one device (ESP-12E) says it is off line, but still responds in both directions.
Is there a forewarning of app updates that I am missing?
Blynk is a great app.

Always a good idea to keep Local Server, libraries (NOTE: requiring re-flash of MCU sketches) and App updated to latest, as they are all related. Often an update in one will not work or cause issue if all others are not also kept current.