Data Bags: Can't upload entire data bag

We're running Chef 12.13 and I'm trying to upload all my data bags using the following command:

knife data bag from file -a

The command runs without any output at all, but the data bags aren't update on the Chef server. We have no issues uploading individual data bag items using the following:

knife data bag from file all_users test_user1.json

But I would like to know specifically why the '-a' option isn't uploading the entire data bag.