This has happened to me a few times recently: i have a bid accepted for a player from an unmanaged team and a couple hrs before the transfer is due to be completed a manager takes over the side and leaves almost immediately, causing my deal to collapse in the process. I had a look at the profile of the most recent manager to do this and in a 2-hr period this person took over and left 7 teams.
I can accept that something like this will happen from time to time, but it seems as though this is deliberate attempt to block transfers, especially as there's a ~7-day ban when a manager leaves a clu