Weird issue with parts of my model being cut off

[Owen2992 0]

I'm very new to 3d printing and this is the first issue I've ran into, I'm not sure why after slicing, its cutting off a chunk of my project

[gr5 2,235]

Your model isn't water tight.  It isn't "manifold".  It is defective.  I can see clearly in the inset below that there is something missing - a wall is missing.  So your walls are actually infinitely thin so cura prints them infinitely thin (meaning it exudes zero filament).  The real question is why did it print anything at all.

 

Is this your model?  Can you repair it?

 

There is a cura mesh plugin that might fix this but I'd fix it in CAD or try some of the online STL repair websites.  Or use meshmixer perhaps - I think it might have a repair function.  here's an online repair service.  I can give you more options if you want:

https://3d-print.jomatik.de/en/index.php