Problem solved, sort of. I was using 0x76 as the address for the most recent tests. I switched it over to 0x77 and everything works. I reverted back to the stable firmware build and it works there too. I was using the correct address in earlier tests but changed it over to 0x76 to see if that did anything, apparently I forgot to change it back. Either way, it seems to be working, so I'm not going to dig into it any further.
On a side note, I'm getting odd readings for temp. When I put my finger on the sensor, the humidity goes up as expected, but the temp barely moves. Is this something you've experienced?
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Thank you! I was getting really mad with a clone BPM280 being unstable in operation and giving random errors as shown in posts above. Since I changed the address 0x76 to 0x77 I am able to run stable the esp8266 (NodeMCU 12e) powered from battery and publishing to a mqtt broker. The main interesting fact is that running the i2c python scanner indicated the 0x76 as the address of the device. Thank you once again, I was ready to give up not reaching the happy end of my first project
