Have you removed the rear glass yet? You can move it a bit before tightening the little screws. If you haven't tried already just loosen those screws and rejigger it a bit.

I'm not really sure I didn't have these problems you're describing. Which I guess is no surprise these things are a disaster. Recently I have opened the headliner a couple times and got lucky but haven't opened the glass since last summer.

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'05 E53 3.0 6mt
'17 F30 340ix 6mt
'96 E36 328is, in progress