I am taking a prescribed dose of vyvanse, (lisdexamfetamine) and also prescribed oxycodone. Last urine test showed hydrocodone, no o-oxycodone. Could Vyvanse (lisdexamfetamine) cause this?

Test limitstion. This is a limitation of in office urine screen testing. The kind that are commonly used have a high error rate. The next step should be sending the urine out to a laboratory for confirmation. The tests done there are highly accurate. Office cup tests are enzyme linked immuno-assay, laboratories can do a test called liquid chromatography/ mass spectroscopy.
No. If you tested postive for hydrocodone, you were taking hydrocodone. Some simple urine tests do not include oxycodone; make sure it was included. If this was a gas chromatography urine testing then there are no false positives and the oxycodone or its metabolites would have also been identified. Talk over the results with the ordering physician.