Options Missing in Dependent Dropdown List Fields

Issue:

The dropdown list is missing options.

What to Check:

Do the necessary custom record instances (for example, Vehicle Model records) exist and are they active?
Are the controlling field values set correctly on each record instance?
Are any of the records or options set to inactive or restricted by permissions?
Are user roles and field/record permissions correctly set?

How to Fix:

Verify all necessary record instances exist and are active.
Confirm each instance is linked to the correct controlling value.
Review permissions and field access, and test as different user roles if needed.