Large area of a model filling in when it is not supposed to

[Gamester]

Hello folks,


I'm new here and am also new to 3D Printing, but not new to 3D modeling.

So I have recently obtained an entry level 3D printer, the XYZ da vinci jr. printer and I really like it. For the most part, I'm picking up on this new to me world pretty well and have already made some great prints with it, however I have run into a snag with a model I am working with.

So, the model is supposed to look like the first attached image. However, when loaded into a slicer program, in this case XYZprint, and when actually printed; it fills in the whole inner part of the model like shown in the second image, which does not make sense to me as that is not how the model is made and I have not had this issue with other models so far.

This is a fairly simply shaped model and I don't know what the issue is as the reverse side of the model prints perfectly fine.

I've made sure that this unwanted fill in is not being caused by the slicer program as all fill in settings are even turned off right now.

I'm guessing there must be something simple that I'm missing here causing this, but I just don't have enough experience with this yet.

Also, the model is an STL file and outputted by Blender if that helps.

Any directing help I could get here would be greatly appreciated!

Thank you,
Gamester