For Windows I just learned that you can get the "SemanticImport::unexpinvaliderr: Unexpected invalid input was detected. Processing will not continue" message, if the name of your "TemporaryDirectory" contains a space.
So you can solve it by setting $TemporaryDirectory to an other existing(!) directory (or create it first) without a space in the name. Example:
CreateDirectory["C:\temp"]
$TemporaryDirectory = "C:\temp"
This is propably the reason why SemanticImport, works for some and not for others.
I don't know if the same is true for Mac OS.
