Gaps in support layer, even when interface line spacing is set to 0

Hi all, I have an issue in Bambu Studio where the support interface will not close up no matter what I try. The interface is 3 layers with ironing. This causes defects on the bottom surface of the model. I’ve tried changing support line widths, wall generation type, x/y distance…Nothing works.

Any bright ideas? Thanks.

Can you attach the .3mf file?