As far as I am aware, firmware 2.1.7 handles both types of RTC that we’ve used previously:
https://github.com/OpenSprinkler/OpenSprinkler-Firmware/blob/49f0c3dd8ce5501ae88b810412ecd5e157754aa3/DS1307RTC.cpp#L40
so I honestly can’t explain the symptom you are seeing. As I said, I have a test OS 2.0 and I don’t observe any RTC issue as you reported. If you suspect it’s the RTC, can you take a look at the RTC you have on your board and find out the part number?