I am trying to make the switch over to Blender 2.8 so I am doing some small projects to get started.
I have attached a few images to illustrate my issue I am having with the boolean modifier.
In the first image you can see the shape that I want to make, its pretty simple just a tunnel. I created a cylinder and I just want to boolean out a rectangle to. When I go through the process it doesnt seem to cut out the bottom of the cylinder.
That’s the oddest thing. I ended up just recreating a cylinder that was kind of like yours and the Boolean worked there. I think that if you were to start over with your cylinder and recreate it, it would probably work for you too. Here’s a test blend.
Ahhh yes, as @tricotou mentions, I didn’t check the geometry of the mesh but yes there is geometry issues with it so that needs to be fixed for the boolean to work properly.