Help needed -slicer fills hollow object

Hi all
so I got this head, part of a larger project. It’s hollow, there will be cables passing through. Bambu studio sees the object right, just like designed and exported in Blender, but refuses to slice / print the hollow tunnel and completely fills it with infill.
Is there a setting I’m missing?
Thanks!



You wouldn’t happen to have like a STL file to check?
Blender is good for many things but often creates mesh or manifold problems.
No problem in anything else than trying to print those.
I had a similar nightmare with a really basic, cylindrical coupler.
Though I did it great in those almost 5 minutes to model it but there was ONE reversed face and during the STL export this turned into something else - a non existing horizontal face in the middle of my coupling tube.
Tried for hours to work out why it won’t slice while showing fine in the prepare windows, even tried to do a test print at small scale…
Came out without this separating wall but a lot of strings where is was supposed to be.
No manifold complaints from the slicer either…
Not saying your exported model file IS the cause but I would like to rule it out before this turns into a nightmare of trying different print and slicing settings for no reason.

Can’t see it clearly in the first pic but looks like some wall issues at the bottom of the hole, unless this is a spare out area for a snap fitting or such.