you may check if this works not just by number of thread but also by tile limit itself. If you see three threads limit, then it works because default is 2 or even 1. So one small sorry for this, because I thought limit will be increased to 5, but as I look into code, it's only 3, so changed now.
Also on your own server is limit to 10k tiles per day, this should be also removed with this also in current version
Also on your own server is limit to 10k tiles per day, this should be also removed with this also in current version