Have you had this working in previous characters? If so, then maybe when you ran the script something didn’t link up. You could tray expanding the ankle joint expression and checking the toes match the settings. Alternatively if you have used this in the past, then you could try starting again.
If this it the first time you’ve used it in this way and it happens again, it might be a bug in DUIK’s code. They’ll thank you for reporting it.