Checkbox isn't disabled in inherited "CSV to JSON" preprocessing step

Steps to reproduce:

1. Create template with item (Item prototype, Discovery rule)
2. Add "CSV to JSON" preprocessing step in item
3. Link template to host
4. Open inherited item
5. Open preprocessing

Result:
Checkobox "With header row" of preprocessing step "CSV to JSON" isn't disabled
Expected:
Disabled all fields of inherited preprocessing