There's a known bug in hivemind that causes this and I raised the issue with our devs last week. Your follow list isn't really lost, it's just hivemind is interpreting the data improperly right now. I actually had a meeting scheduled today where I was going to check on the status of this issue, but the meeting got canceled due to sickness (not mine, I'm fine). Anyways, I should be able to get an update on the situation tomorrow. In the meantime, rest assured it's a temporary problem and none of your info is permanently lost.