I found a workaround at least for ONE window arrangement.
Open all plugin windows you want to have visible, resize, arrange, whuteva. Then press F12. All windows will disappear.
Now work normally but use F12 ONLY when NO OTHER plugin window is open. F12 will then bring back your custom window arrangement. Any extra plugin window opened while the "special arrangement is also open must be closed before using F12 again.
A pain in the butter but I must be able to quickly have 16 channel strips visible at the same time. The odd thing is that unless you recall the custom arrangement prior to saving the session, it gets lost upon reloading the session.