Important to all using tasmota on esp8266
You must use hardware serial port or it misses a lot of data as timings get garbled using softserial that shares timers with wifi.
Use port 3 RX and 1 TX like bellow:
+1,3,m,0,9300,EB,1,…
Some devices (eg. wemos mini) need to unsolder the resistor close to the RX port or it gets stuck high.