I found that when I put more forward lean on the highback it made them spring up more when I tried to take them off. I just kinda dealt with it, and would bend over and hold the highback down while I pulled my foot out.
Flows can be a real pain to set correctly, but once you get it they are very handy. Just keep working at it, and remember you can get them too tight. Play around with your highback lean angle as well, because that will make a big difference in the feel of the bindings.