Cura is slicing my object (a gear with text) with a partial top layer, and I believe it has to do with layer height and rounding issues. I have been able to solve this at specific heights 10-14mm using a layer height of 0.25 mm, however other heights will cause this issue to arise again. There must be a solution to this that doesn't require the user to constantly be adjusting layer height and object height in order to resolve what I perceive to be a rounding issue.
Here is the model: https://filebin.ca/3f2g2s0dklzR/hackEly_v1.0_joined_text_2.stl
I don't believe that this is not a non-manifold issue. I have also tested this using a gear without text.
Like I mentioned, I can get rid of that layer division at certain layer heights and object heights (e.g. 0.25mm layer height), but I would like to find out how to get rid of this issue regardless of object/layer height. Thank you for your help.
Your model isn't perfect. I took it into Windows 10 3D Builder for simplicity. I kept clicking the "Mirror" function and noticed as it basically flipped there is some slight movement. I measured some points from bottom to top and noticed some differences.
Try to take your model into some software to fix/flatten it. Or recreate it making sure its perfectly flat on both sides. It is definitely not your Cura software.