We are aware of this issue and are actively working on a fix. It should be resolved shortly. We apologize for introducing this bug.
Unfortunately this is still occurring. The search is not looking at groups or tags, only item names. This is extremely problematic. We are a week away from launch and now have to reconsider whether to use this as a tool or not. Without proper search, it's not useful. We need some assistance with this and fast.
After dropping some tags and re-adding them it appears the site re-indexed and tag searching is working again. Group queries are still working though. Progress and should help us with launch but we've got some reworking to go back and do now because we were going to heavily use groups instead of trying to manage tags which can be like herding cats.
So, here's to herding cats.