It has come to our attention that using the ComfilePi with a 1-wire sensor, such as the DS18B20, can be problematic. The problem seems to be caused the the transparent level-shifter added to the I/O pins for ESD protection. That isolation appears to cause a signal reflection on the I/O line.
A potential solution is to add a small resistor (e.g. 100Ohms) to the I/O line to dampen the reflections.