How to do this:
1. With the user account that deployed the solution access the workflow that isn't visible to other users.
2. On the workflow designer click the green 'File' button. In the dropdown click 'Share'.
3. On the Sharing settings screen you should notice the account that deployed the workflow. Utilize the people search bar located to the right to search for which users should be able to access the workflow.
4. After making these changes deploy the workflow.
After you have made these changes the users that were previously unable to see the workflow should now be able to.