grim, when it’s like that don’t update your server before testing, you will be able to joined it if you make steam wait to launch for update for ark and launch ark using the binaries file in the steam directory. so it will launch without doing the update 
that’s the only way to never loose anything between patch, since we can’t rollback between the version 
the problem is that you need to be able to launch another server, and need to have 2 ark, one update the other not ^^ (didn’t try to copy the ark folder from steam and launching it like that maybe it work)