I would recommend to create a techsupport case on the matter as it required to be investigated in details. Your element configuration may be required for investigation.
How does analysis updates the value - by numeric value in enumeration set or by the according string value? It could be that according string value cannot be correctly written to the Enumeration set attribute. Can you try to write according numeric value?
Again, I think it will be better to create a techsupport case.