82-218 just won't fit

I tried to replace my mortise with your 82-218.
As you can see, it looks identical to me. However, in addition to being very difficult to get the old mortise out (that's how it got damaged), I can't get the new one in.

it looks like there's a bar running up the back of the mortise cavity, making it less deep than I need it to be. is that possible

Like I stated before,there is a metal bar inside the door frame. The original 82-218 had to be forcefully removed due to the fact there is only a 1-1/16" space where the mortise latch fits. There was no play at all to tilt the new latch into the mortise and once in pull it forward to secure it to the outer frame with screws as shown in your video. It appears that the latch may have been installed before the door was assembled. I noticed that you sell a similar latch
that has the rear corners that are cut on an angle. I wonder if that would make for an easier install? I could not find the manufacture of the door, but there is 3 doors that work together,and each door measures 4ft wide by 8ft tall.