Update: I eventually fixed this by changing the pullup resistor for the DS18B20 circuit from the usual 4.7k to 2.2k.
See here: DS18B20 not working on 3.3v?
Update: I eventually fixed this by changing the pullup resistor for the DS18B20 circuit from the usual 4.7k to 2.2k.
See here: DS18B20 not working on 3.3v?