The XT cameras usually show low battery before they are really dead. Typically however, one battery will be dead and the other one is still full charge.
Dead = 1.3 volts or lower.
Good = 1.5 volts or higher.
The XT-2 cameras are new so no pattern on this yet.
If yours are all XT you’ll have to work with tech support for a real solution. Having the latest firmware in each camera and latest mobile app version will be checked and confirmed.