The other day we altered the hours (in Appointments+) under Appointments > Settings > Working Hours and for some reason the follow dates became blocked out as "busy" - April 5, 12, 19, 26 and May 3. Oddly these are all Wednesdays. After that the Wednesdays open up again so visitors can book appointments. We have no idea what is happening.
Those days haven't been blocked in our Google calendar either.