Since you have jazzmin installed, it's highly likely that jazzmin is overriding the default Django admin templates and causing the length_is filter issue. jazzmin customizes the Django admin UI, and it may be using a filter or customization that isn't compatible with your setup.
Since you have jazzmin installed, it's highly likely that jazzmin is overriding the default Django admin templates and causing the length_is filter issue. jazzmin customizes the Django admin UI, and it may be using a filter or customization that isn't compatible with your setup.