I have notes in my Sous Vide diary (copied from egullet @nickrey said 162ºF for 48 hours and @FeChef 160ºF for 24-30 hours). I started at noon on Saturday and was done by Sunday at 5 pm - 29 hours. But that cook was more than one year ago.
I think I would move the oxtail to the Anova oven (APO). Perhaps this as a guide? Jamaican Style Sous Vide Oxtail
Personally I am very annoyed by oxtail in the general grocery stores, the oxtail is sold now with an extra inch of fat around every piece. Which is a lot of money to toss out. Grrr!