otter-grader: Otter assign - tests fail when answers are correct, "Error: object not found"

Describe the bug I am following the otter sample at https://github.com/ucbds-infra/ottr-sample to create an assignment, and all of my tests are failing on Gradescope in the tested Rmd submission (a submission with all correct solutions). It is notable that all tests pass successfully when testing locally using otter run lab04.Rmd. I am attaching a ZIP file containing the master notebook file that I am using and a screenshot of the failing tests. It seems that the tests are unable to recognize any of the variables that are created in the immediately preceding solution cell.

Archive.zip

To Reproduce Steps to reproduce the behavior:

1. Unzip the Archive.zip attached. cd into its directory.
2. Use Otter assign to prepare the autograder.zip file: otter assign lab04.Rmd dist. Note that the header of the master notebook has the following:

BEGIN ASSIGNMENT
requirements: requirements.R
generate: true

1. Upload the autograder.zip from dist/autograder to Gradescope.
2. Test the autograder using the solution Rmd file.
3. The above error is produced.

Expected behavior All tests should pass successfully for the tested submission .Rmd file on Gradescope.

Versions Python version: 3.9.5 Otter-Grader version: 2.2.2