Are you planning on doing the printing and wrapping yourself?   Do you use a custom colour lab?  I use OnOne’s perfect resize to prepare files for canvas mounting.  It does a really nice job.  If you know your frame is 1.5 inches you can input the measurements to add an extra 1.5 all the way around the print size you want.  Lots of options for the wrapped edge too, i.e. solid colour, mirrored from the print with any opacity you want etc. 

I’ve been using Aperture since 2007 and I have never thought about how one would or could do that in Aperture only.  I might be incorrect, but I doubt that you can.   

The colour lab I use has a section for canvas where the templates or nodes for various size canvas prints have a thin red line showing what will be lost due to the wrap. 

Strange about apps TK.   I don’t have a PhD in Geek, not even high school in it for that matter, so when something goes wrong I’m usually lost.  I started with Aperture when my son convinced me to start using Macs and it has proven very reliable over the years.  Hard to believe that Aperture was developed before Lightroom.  I’m very disappointed that Apple is no longer supporting Aperture but I’m keeping my fingers crossed that the new Photos App will be every bit as good and even better than Aperture.  I just can’t see Apple wanting to loose their serious amateur, hobby business and pro Togs to Adobe but perhaps we are such a small % of the overall market that it wouldn’t matter to them.  Hope not.  Sorry to hear that there is some type of glitch with your system, perhaps the new Photo App will work perfectly for you.   Cheers!