[Bug on current tool] Cannot add Preferred Repositories or Metadata Standards to Template Preferences

[bofstein]

Describe the bug
Trying to add Preferred Repositories or Metadata Standards to a Template's Research Output Preferences gives a 500 error and does not save selection

To Reproduce

1. Open up any template on Stage or Production (use an unpublished or demo one to avoid affecting templates in use). You can also create a new one and the same thing happens.
2. Enable the Research Outputs tab in preferences.
3. Check the box to "Create a list of preferred repositories." (or use Metadata Standards, or both - same experience)
4. Select one or more Repositories from the list as preferred, then close the modal window.
5. Click Save at the bottom of the page.
6. Observe the 500 error.
7. Go back to the Preferences page by hitting the Back button and clicking on the tab, and observe that the selected Repositories are not saved.

Expected behavior
The selected repositories should be properly Saved to the Template preferences without error.

Screenshots

Additional context
This is happening on both Stage and Production sites, and for both brand new and existing templates.