When loading a session minibufexpl is empty until you do something with the buffers

[bliof]

When you do :mksession tmp.vim and then you do something like vim -S tmp.vim you will get a warning/error "-MiniBufExplorer-" [Not edited] --No lines in buffer-- ((1) of 2) (As far as I can tell, it opens the buffer/split from the session file). The split that was saved in the session is shown on the top and it is empty. You will have to do something like :bp and then minibufexpl will fill the split with the current buffers.