I was surprised today to find that the next usable backup according to Timemachine is from March. Other dates show up in Timemachine but are not selectable. They are light-blue and only dark-blue dates are selectable. The two most recent entries are "today" and "July 20" and the two most recent dark blue entries are "today" and "March 3". I checked the Timemachine disk and it has a folder for July 20 and all the files are in there (using hard links, I think). Why would Timemachine not recognise certain folder it had created? What would have happened if I had needed to restore from that point in time?