The sv_region setting would've been in your server.cfg file already. If you added it a second time but higher up in the file, it will run set it to whichever setting is listed last. Also, setting it in the autoexec.cfg file doesn't do much good, since that file only runs once on startup before the server.cfg file is run. In addition, our systems will automatically correct the setting on managed servers and standard game server rentals.
I should also point out that setting the server to 0 also lists the server under region 255, while setting it to 255 is the same as setting it to anything else but without the specific locale also being added.