I used esp8266 esp7 tx serial out to drive the digole lcd 1602 display without any problems. When I changed to esp8266 esp12 same software does not work with the lcd anymore. In both cases a monitoring pc connected to the tx esp8266/rx dogole serial adapter will decode what esp sends out to lcd with 9600 baud. A scope analysis did not give any relevant differences, except a smaller gap between words for esp12. Any ideas how I may solve this issue?

The digole power supply was 5.15V from a wall wart. When accidentally lowered it to 5.05V  the display worked for a while. The serial input comes from 3.3V logic. Still trying to figure out.