If an entitlement script is added to a catalog item, although commented out, it is still evaluated to false and causes the item to be hidden.
It also overrides any other types of entitlements like Available for group.

In Fuji or Geneva perform following setup:

1. Turn off the property glide.sc.use_user_criteria and set to false.
2. Visit a catalog item and add a group under Available for groups.
3. Ensure that the group does not contain any special roles as they might override the error behavior.
4. Add a newly created user to the group.
5. Impersonate the user added to the group.
   The catalog item should be available in the service catalog.
6. Stop impersonating the user.
7. Open the catalog item.
8. Add Entitlement script to the form.
9. Add an entitlement script that evaluates to true and then comment it out. For example:

/*
answer = true;

*/

This evaluates to false, when it should behave exactly like an empty value and evaluate to true.

Having no code and just comments in the Entitlement Script results in returning a false condition and hiding the items. The workaround is to have an empty value and not just comments.

Ideally only comments should work as empty value and should return true value, so that the item is always visible. But this would not be fixed as entitlements is legacy behavior replaced by user criteria.