This looks to be a problem with the location field. The location for Financial Transactions are client configured locations that identify the place that the bill was posted from. However, currently there are no location IDs in this domain. The location field is also optional, so for now I would omit the location field all together, and that should allow you to continue testing.
We will work on making sure there are locations in this domain soon so you are able to test with the location present as well.