I'm connected to a 5v heat-pump to control it via serial. I'm using a level shifter to shift between the two as the heatpump is 5v and the D1 is 3.3v shown in the scope images below. My issue is I can't read data off the RX line as its voltage is wrong but only when connected to the D1. If I remove the D1 RX pin the voltages are shifted correctly.
So the weird voltage issue only happens when it's connected to the D1. I've three different D1 chips (given they all came in the same batch) with the same results. I don't think it's the shifter because of what I see in the last scope. Any idea what's going on here?