Good afternoon, this is Solidworks 2012.

When I try to add ANY additional lines to an existing flange (in places where there are no bends), solidworks automatically tells me that half of existing bends fail, with errors:
"Please make sure that the selected fixed face is the face on which the sketch has been created"

I try to re-select the sketch plane, but the error never goes away.

furthermore, when I try to undo any of the new features added to the flange, the changes are reflected in the sketch, but the errors are still there.

Therefore I believe this to be a bug in Solidworks.

The part is attached