How can I cut a tear shape into sheet metal pipe and convert it to flat pattern

Hi there,

I am currently designing an outlet for a piece of equipment and I am having issues converting the piece to its flat pattern. This is the final product:

I am attempting to select the sheet metal piece which is a section cut from pipe in solidworks. I want to then convert the piece to its flat pattern so that I can convert it to a dxf and cut it from sheet metal on plasma cam. The following are the steps to creating the first version I attempted that worked in the program just fine:

This is the first cut in the sheet metal pipe. This angle is what determines the height of the piece when attached to the outlet. The second/final cut is simply a right angle to the original cut that also passes through the vertex of the part:

The next step is to simply unfold:

Now this works great as you can see. The issue comes when I want to increase the height of the outlet to allow for more airflow. Below are the following steps:

The height of this piece is just over 1.4, whereas the base is the normal length of 1.25 (though not labelled in this picture). The next picture is the issue I am facing:

It appears that something to do with the dissymmetry between the lengths is preventing the part from being unfolded. Any thoughts on how to skirt this issue?

Thanks!