in normal view of presentation the menu-item "presentation->start with actual slide" does not work, menu item is greyed out in slide sorter it is possible to start presentation via menu item "presentation->start with actual slide" or by pressing F5 (I changed this in the options from Shift-F5 to F5 because I am used to this) I think this is a bug.
I have the same problem but it's even weirder. I am teaching a workshop using two presentations. On day 1, I worked with slideshow 1, no problem. On day 2, slideshow 2 has the "start with current slide" menu function greyed out. So I load slideshow 1 again to see what happens there and - first, in that slideshow, "start with current slide" was not greyed out and it worked; - but 20 minutes later, it is greyed out there, too. Using 4.2.4.2 on Kubuntu 14.04 64 bit.
*** This bug has been marked as a duplicate of bug 76953 ***