Whats happening to you is unusual but don't worry yet. I think it's still manageable but it depends on your case. If you did provide the documents as Singapore visa office asked and followed their guideline, I think you can relax.Can you let me know when you first applied and since when you are in Received by Visa Office stage? Also your qualifying NOC and University name and subject you studied in University is important to know.
This is the only chance you get for defending your educational claim. Of course they received your documents but check with the University as well. You can also take some other measures to defend as this is the only chance you will get. SGVO will never say whether they are satisfied with your recently sent docs or not. You will have to wait and find out. Suddenly one day you will just see the next stage in ECAS or the dreaded status in ECAS. But what to do or how effective your new defense is going to be depends on your case, as every case is different and why the problem arose in the first place. So please let us know some more details and I'm curious about another thing, did you send your educational certificates (notarized) and Official Transcript (not student copy) in a University sealed envelope as per the CIO checklist?
May Allah help you in your troubled time. Don't lose hope, you still have very good chance for getting what you want. Just because they asked for some documents doesn't mean you are in a bad position. So not to worry. InshAllah everything will work out. You can send me PM if you want or here too.
BR
munnabd