boolean difference working weirdly So I am making a cassette tape

the body of the cassette tape (yellow outlined in the picture) is a single object
I added boolean modifier to the body and set the white cylinders protruding in the middle in the picture as a subject.

Now when I hit apply, the hole appears only on the right side.

I checked the mesh in edit mode and the left hole is also there but its not showing up correctly/
How can I fix this issue?
This has been asked before in different ways, so you’re not the only one. The Boolean modifier typically runs into problems with miscalculated normals, so double check your normals in both meshes. If both sides have the same wrong result, check the mode setting on the modifier. If the results are not the same on both sides but you’re sure the normals are correct, you might have some non-manifold mesh or micro-faces somewhere.
Edit: looking at the hole, and thinking about what you want, I recommend calculating the cutting cylinder’s normals to its inside, and using the “union” mode on Boolean. I could be wrong, though.