Reusing some previous assignments does not work

I'm trying to reuse assignment from last year. However after selecting organization and class, I received this error

Reproduce the workflow described in the issue by selecting an organization and class, then inspect the error shown in the attached screenshot. Trace the assignment-reuse entry point and identify the failing step; done means assignments from the previous year can be reused successfully after those selections.

Written by the indexing model from the issue text.