This is your answer. Do not aim that to hit the center of the pocket! Aim it just like he said above...the pocket facing of the short rail. If you do that it goes in. If you hit it slightly thick it still goes. If you aim for the back of the pocket the long rail is in the way.
I have been meaning to do the following, and reading this thread is motivating me to do it. Place a video camera on a tripod so that you can record a nice video of the OB coming down along the long rail. Note, for each of 100 shots whether the OB is hitting the long rail, and where on the long rail it is landing. Likewise, note how many times the OB hits the facing on the short rail, and how many times it hits the point on the short rail. Do this with the OB and the CB in slightly different places each time, with slightly greater and lesser angles (but with all of the shots being essentially the shot portrayed by the OP). Repeat with the CB at a still slightly greater angle, and then at a slightly lesser angle. Etc. Don’t allow yourself to “groove” any given shot. The idea is to generate data reflecting how your brain is working before getting recalibrated through dedicated practice using donuts, etc. This will allow you to see exactly what your proclivity is, e.g., to know whether your most common outcome is to hit the long rail between one and two diamonds from the corner pocket, or at some other point. The value of this recording is that it reveals what is somewhat difficult to see in real time (exact landing spot) unless you are not staying down on this long, down the rail shot. It also allows you to measure success based on where the CB is landing, and not on whether it goes in the pocket. Simply calculating one’s make percentage is not a particularly valuable exercise. Say you make 8 out of 10. Great, but wouldn’t you rather know that 6 of the 8 hit the long rail between half a diamond and one plus diamonds away from the pocket and only went in because you used pocket speed?