When you propagate multiple ports, and an expression or condition depends on more than one propagated port, the Designer does not propagate attributes to implicit dependencies if the attributes do not match.
For example, you have the following expression in an Expression transformation:
Item_desc_out = Substr(ITEM_NAME, 0, 6) || Substr(ITEM_DESC, 0, 6)
The precision of Item_desc_out is 12, ITEM_NAME is 10, and ITEM_DESC is 10. You change the precision of ITEM_DESC to 15. You select parse expressions to infer dependencies and propagate the port attributes of ITEM_NAME and ITEM_DESC. The Designer does not update the precision of the Item_desc_out port in the Expression transformation since the ITEM_NAME and ITEM_DESC ports have different precisions.