I redraw from 0 the disc /cylinders... not on the generator curve (maybe not the root problem but more prudent! :)
(not the groove piece you can copy it if necessary...
like this all perimeters are plenty and not trimmed! ;)
So
No problem! :)
https://moiscript.weebly.com/uploads/3/9/3/8/3938813/flange1.3dm
there are 2 models for make yours tests!
Solid ++ or Acis
Chamfer or Fillets 1 mm