WC_PhotoRebooth changes the core vanilla date parameters to suit their needs. Naturally this breaks anything which utilizes that, including this mod.

We have a dirty edit which fixes the issue (although it does break a small part of ReBooth's functionality. Many thanks to Dragon32 for the detective work:

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Comment out the lines (add a ; in front of) in the "[X2StrategyGameRulesetDataStructures]" section of that mod's XComGame.int

m_strMonth0=JAN
through to
m_strMonthDayYearLong="<XGParam:StrValue0/!MonthString/>-<XGParam:IntValue0/>"