@mcgreg There are many possible things… Multimeter is not good enough always because of changing internal resistor. Use CurrentRanger or 10ohm resistor in series together with osciloscope and chech your power consumption during transmission and sleep. My RFM95W takes up to 130mA in transmission. Your I2C bus can drain current through pull-up resistors if something is changed on Arduino side.
Also problem can be in batteries. Not all baterries are the same. They are in the same package and some can have just half or double capacity. It depends also what is their cut off voltage. Maybe it is not going in sleep all the time.
First thing is to know real consumption during few cycles. After than you can start looking where is the problem. 
I’m doing master theseis survey about LoRaWAN development and testing (your experiences, habits and practices).
I will be thankful if you fill this survey. It will take you just couple of minutes and it means to me a lot! 
Thanks 