Hi Charly,
Please make sure all the dimension member mentioned in the affected formula are valid member id representing each dimension and are base member. Also, make sure that there are not more than 1 ID per dimension in the EPMSaveData formula.
If you are not mentioning the ID from all dimension in your formula, those members will be taken from the context for the respective dimension, so ensure they are base members as well.
Regards,
Kalyan.