Hi @pio,
The only workaround right now is to reinstall KNIME AP in version 4.5.1 (or 4.5.0 as others have stated).
We are working on a fix for the upcoming bugfix release (4.5.2) which should arrive very soon. If you wait for the bugfix release, you don’t have to reinstall KNIME AP but updating will work.
Update: KNIME AP 4.5.2 is released. Updating to 4.5.2 fixes the issue.