There are a few tags that have no questions. I think these were previously attached to questions which have been re-tagged. For example, I changed timeseries to time-series on one question. Someone else has retagged baysian as bayesian. But the old tags, now without questions, remain on the list and will pop-up as suggestions on future questions. Is there a way of completely removing these tags?
Just a guess- but I have noticed delayed reactions to changes several times today. I'll bet Stack Exchange is trying to be efficient by only examining global tag usage and adjusting every half hour or hour or something similar.
The test would be to see if these tags disappear after some time elapses.