rjbull: I am running this program now. I set the Popup key to ctrl+V.
Not sure about this, but, Ctrl-V is the standard Windows key for Paste
in just about all programs. You may have a conflict, i.e. ArsClip has let you define a key that can't really be redefined. Suggest you temporarily try, say, Shift-Ctrl-Z for the popup, which is what I've used for ages and works well for me, and see if it makes a difference for you.
ArsClip 3.1.0 also defines Win-V for Paste Clipboard as Plain Text. I don't know if there's any conflict there as well, but it seems to work OK here, not that I often paste fancy text.