[ { "geometry": { "hasZ" : false, "hasM" : false, "paths":[[ [504341,798781], [504192,799065], [505341,795781] ]] } ,"attributes":{} } ]
I had the same problem, but I had a date field that was incorrect.
I had this problem as well, it turns out that I had used another layer as a "template" when creating this layer, and it copied the Shape.STLength() field to Shape_STLength__. I was doing this in a python script so I just did a quick test to see if the Length or Area columns got copied funny and if they did remove them. The Shape_STLength__ (and Shape_STArea__) field is not used by anything, it just causes grief.
The real field Shape.STLength() is not actually a field in the database just a pointer to the length of the actual shape column.