I updated my collars and unit again three different times last night... same problem. The collars will pick for a minute or two... then it will drop them. Every now and then they will pop up, then drop again. They worked fine before the upgrade... I contacted Garmin, we'll see what they say.
When Curr Dog and I updated my collars it was doing something like that. We were standing close to a metal building we think was causing the problem so we moved away from the building and it seems to be working fine now. I think that was the same collar that we picked up for 2 miles...