The BWV standard view studios (and thus also 2BRs) disappear during
DVC's high demand season, which runs from late Sep to marathon weekend in Jan, before or right at 8 a.m. at 11 months out about 60% of the time. The issue you had is common during that period in that the winners at 8 a.m. are the ones with the computers that communicate faster with Disney's computer than others. Sometimes, if you keep checking, you can find what you want because walkers pass by, but even then it is usually difficult to get all the consecutive days you want and thus you should put yourself on a wait list early.
As to reasons for the extremely high demand, they are multiple. Disney's creation and expansion of events in the period (Food & Wine, Halloween party, and Christmas events and decorations which now start going up early Nov) is one factor, mostly ideal weather another, and having most of the period in the low adventure and choice point cost seasons still another. The aging DVC population is another in that there is a continuously growing population of aging owners at BWV, which no longer needs to follow school schedules and is picking the fall season because of the lower points, events, and ideal weather, and many of those members are now seeking studios when before they needed 1BRs or 2BRs. Then you have many resale purchasers over the years who have purchased add-on size contracts, e,g., 50-100 points, from original owners who had mutltiple contracts, and then beginning in 2009 Disney slashed the minimum purchase requirements for new purchasers to 100 and at times to 50, and thus it could sell points recovered via ROFR of larger resale contracts in smaller increments to new owners. The net effect of the low point resales and low point new purchaser sales after Disney exercised ROFR was to actually increase the total number of owners at BWV by 1500 since 2008, a large percentage of whom purchased only enough points to get studios and have a high desire to get the cheapest studios in those lower point fall seasons. The 11 month issue for BWV during that fall season has developed in the last six years. Before then it did not exist for BWV except for a small risk otherwise during Christmas week and the first week of Dec (DVC's highest demand week of the year). It has now spread to that 3 1/2 month period from late Sep to marathon weekend in Jan and become a serious risk. The recent remodel of the BWV studios to hold five instead of four will likely make it only worse.