I made myself admin and it worked 3 times in a row. Weird you're having so many issues. The normal pit window will pop up but after your time delay the auto pitstop kicks in.
Strange how it works different for me, did it work for you on multiple pit stops. The logging as admin is an unrelated issue but Ive never had that happen in a server before so its something odd to do with the plugin.
If Thursdays are still on a fun run it may be good to give the app a try there with more people.
It's worked every time for me, on numerous connections to the server. I haven't seen a single problem. I've become admin, Joe's become admin, and it's worked for us.
I can see this in the server logs every time you become an admin (I removed IP addresses):
22:58:01.600759 Making Marty [Achilles Heels] admin
22:58:05.079676 read tcp x.x.x.x:nnnn->x.x.x.x:nnnn
: wsarecv: An existing connection was forcibly closed by the remote host.
22:58:05.081661 Connection is now closed for Marty [Achilles Heels]
I have no idea why becoming admin doesn't work for you. Don't become admin, and you won't have a problem
I'm still looking into why you might be getting this error though.
This post of yours Marty is interesting: http://www.assettocorsa.net/forum/index.php?threads/minorating-com-drivers-thread.25732/page-104#post-720745