Hi @fbeiger after long research, the issue probably come from the definition of two smart action.
One based on Agency model with Exporter les leads name and on the field Tags (au moins un des tags sélectionnés).
And another based on AgencyFeature model with Exporter les leads name and on the field Tags (au moins un des tags sélectionnés).
All these fields are ['Enum'] type and the enums option does not allow null value.
Can you remove this options and restart your server please? And let me know if it fix your issue? 