Adding a blank slide to a software simulation

Hello all I don’t know if i am going mad, but i am pretty sure that in the past, i was able to add blank slides to the beginning of my software simulation, but I am no longer able to do so.  I am also pretty sure that i could shuffle slides up and down in the filmstrip, but again, I am unable to do so as of a few days ago.  Is anyone else experiencing this issue?