Here+ Base Station Won't Survey in Less than 12m Accuracy

I’ve been using this base station for a few months but lately it occassionally won’t survey in less than 12m. It usually takes 5 mins to survey in to accuracy of 2m but occassionally it won’t drop below 12m. What is wrong?

The issues is independant of location and proximity to other structures. I had this issues in 2 different open fields.