I created a level … and now it's gone! And, I can do it again and again!

OK, everything worked fine UNTIL: I added another source check box, plus Tier SER created it automatically. Once I did it, the level vanished !!!!!!! : or

A true mystery, is not it?

I can do it again and again. BUT – U can not use the names of the missing projects. So, where are they? : /

Any ideas???!?!??!??!?!? THANK YOU!!

PS-I've done a lot of times in the past. What happens NOW that makes this happen?