Here below is a default objectivecycle.cfg file that comes along with ET. Check it out and tweak it with your own maps. I see as you tried to do it already, but the cycle was incorrect and it has to return to start from the last map to work.
set d1 "set g_gametype 2 ; map oasis ; set nextmap vstr d2"
set d2 "set g_gametype 2 ; map battery ; set nextmap vstr d3"
set d3 "set g_gametype 2 ; map goldrush ; set nextmap vstr d4"
set d4 "set g_gametype 2 ; map radar ; set nextmap vstr d5"
set d5 "set g_gametype 2 ; map railgun ; set nextmap vstr d6"
set d6 "set g_gametype 2 ; map fueldump ; set nextmap vstr d1"
vstr d1
New update on ETL coming in ~10h, maybe that helps, as there was something mentioned about startup issues that should be fixed.
Other than that, lately there has been many updates on nvidia drivers, so make sure those are updated.