So, I know this is a long shot, but here goes.

I have a number of users (myself included) who are struggling with trim and extend in 2015.

We draw a line. We draw lines perpendicular to that line, but short of the line. We want to extend them all. We start the extend command; we select the first line, and then we window to select the lines we want to extend. The preview shows them all extending, but some of them do not extend. There seems to be no rhyme or reason for this. I was able to get them to extend by selecting top left to bottom right, but a colleague was unable to get the same result.

Some variables:
Edgemode =1
Pickadd = 2 (If pickadd is set to 0, it works, but pickadd at 0 is a horrible option)

Not sure what else I should be checking.

Oh, and when I tried this in vanilla AutoCAD, it worked fine.

Thanks!!! Hope someone knows because I am stumped!