I was working for about 3 or 4 days in DF20 and had it happen at least half a dozen times, but did remember the few steps that led up to the last time. This coupled with the Binary Field bug that I am experiencing has forced me to move my project back to 19.0 so have had to abandon my plans for DF20 at least until these 2 bugs get sorted out. The Binary field bug is a show stopper for me and the studio bug wasn't technically a show stopper but I recognized it as a high risk of corrupting my code and wanted to avoid that. Have a look at the VW and the steps that I logged on the HDE Ticket.