Can only read DS18B20 on USB power

I can't figure out how this makes any sense. I'm powering an Arduino uno with a 9v 1500mA power supply and can't get a reading. But if I power it with via the USB port it works perfect. Is there something to this?

Full circuit diagram? Have you measured the 5V rail is actually 5V? Are you using parasite power mode or not?

Sorry for the delay. I’ve been very busy. Sadly that’s all the help I needed :confused:

I switched it to normal power mode and now it works fine.