LTI placements: Course Navigation and Editor Button not working for new app

[molshausen]

I have been working with a vendor that has little or no previous experience integrating their product with Canvas. My team has worked out enough of the major issues that the app is usable now, but the only two relevant placements that work are Assignment Selection and Link Selection. We would like Course Navigation and Editor Button to work as well, but both result in launch errors. The app is just an external website devoted to digital literacy, and the integration is basically there for login/authentication purposes. Why might those two placements not be working, and what might the vendor have to do on their end to remedy that? Thanks!