I don't think that is a bug. It can take a minute or two for the app to refresh itself after a bike is borrowed and/or returned. In the minute it took you to walk to a station, someone else may have borrowed the last available bike. You might notice this when you see someone borrow the last classic bike. You often have to wait for the app to refresh if you want to borrow one of the remaining ebikes without being charged. Also, if a station is down and shows bikes, but you click on the station and can see the station is down because (for example) it shows 5 ebikes, 2 classic bikes, and 0 open docks, you can tell that the station is down. If the bikes plus open docks does not add up to a full station, either the station is down or (once in a while) there are a lot of bikes at the station in need of repair (with red lights on).