Could you guys please provide the exact examples of the ProxyCommands that you use in your setups?
This will help to understand to the variety of cases and what to focus on first.
ThanksAndrew P commented
Awesome that you are working on this... I have things in my config like:
ProxyCommand ssh proxyuser@proxyhost nc %h %p
ProxyCommand ssh proxyuser@proxyhost /usr/local/bin/ssh-proxy %h