I have a button on my form to go to design view. When I change from form view to design view on a form with a subform, the subform usually appears as a blank white rectangle.
Apparently is "normal" if going from form to design view when subforms are involved (when doing so via code) - but you don't say if code is doing that or closing first. I thought you had to close first but have never coded to switch to design from form view. Idea seems odd to me. Does closing first (in code) then opening in design view solve it, or do you have to do that anyway, which means no, that's not the fix?
You might have to post your db for a solution. There may be something that can be discovered that is being missed. I've tried both methods and can't replicate the problem, but that is no indication that any form tested is like yours with respect to the source for the subform control, source for the subform itself, child/parent links or anything else that can cause this. I'd also guess that there's no issue if the sf is opened on its own. It could take some investigation to figure it out.