I've got the standard bellows on my 45N. I recently started shooting efke infrared with this camera and the sheets mostly had zero detail as if they were very overexposed. I've never had these issues when using my other cameras. So today I was testing some expired 4x5 kodak HSI indoors at the window looking out. No direct light on the camera. Same results so I pulled the dark slide for a bit and left the shutter closed. The processed sheet is fogged everywhere except the rebate area.
Just to be sure, I set up the same shot with the same lens using my 8x10 and a reducing back with the same film holder as before. I exposed and processed the film to find zero fog or funky density issues.

I'm going to try wrapping the bellows with my dark cloth but that's not always feasible in windy conditions.
I'm guessing HSI is more prone to this issue than efke ir820. Anyone else having this issue?