Can you give the following a try:
1. Make absolutely sure there are no other english system prompt updates in "Settings >> System Prompts >> Updates".
2. Go to Digital Receptionist and create a new test IVR.
3. Add "Call By Name" as the first option and apply.
4. Make sure that the "Digital Receptionist Language" is set to the English Prompt set you're using.
5. Apply and then from any extension call that Digital Receptionist and try selecting the "Call by name" feature, do you get the same error?
If this works, go back to the existing IVR and make sure the correct prompt set is selected as the language, maybe even deselect it, save, reselect it and save. Restart the IVR service in "Dashboard >> Services" and try again. If the issue persists, I recommend recreating the IVR.
Note: Restarting the IVR service will render certain functionality of the PBX non operational and may even drop calls depending on the call type.