Floating,
If you have received a paper transfer notice for both your I-131, and you I-485, then stop reading my message, I'm on the wrong track, and I just typed this whole message for nothing.
If you did get a paper notice, then keep reading, I have an idea that you could try.
My case status was incorrect for a very long time. I called about it even before the "wonderful" CSRs were hired and I got to speak to a real IIO directly at TSC in September 2002. They told me that it is very possible that one of the IIOs simply pressed the wrong key and changed my online case status instead of somebody else's.
They told me that the only way to get it fixed was to send a fax to TSC to request to get the status fixed. I never bothered to do that, since although the status was incorrect, it was harmless, and my lawyer recommended that I just let it go. (The status was changed to "Response to RFE received at TSC" although TSC admitted that there was never any RFE sent to me in the first place, so it clearly made no sense.) The status stayed that way until now, when it says it got transferred.
Anyway, I have a feeling, that you may be in a similar situation, particularly with your I-131, since Tampa confirmed to you that they don't have it 4 months after it was supposedly transferred. Its possible that your I-485 case went through the same problem, although you'd probably have to go to Miami in person to be absolutely sure. Especially since your case is a September case, unless you've got a rabbit's foot (that actually works), or some kind of a leprechaun up your sleeve.
Its worth a shot, and it can't really hurt. Try sending a fax to TSC requesting that they correct the online status of your case, also explaining that Tampa has never received the case. Who knows what will come of it. The worst case scenario is that they will just ignore your request.
A small warning though, and this might be good or bad, take it as you will. The IIO from TSC told me that in order to actually correct it they will need to pull my file out from storage. This may cause them to either put it back once its corrected, or they might put it in the pile to adjudicate it. It may also delay the case, but I think the IIO was trying to scare me away from sending the fax. In my case she was successful. Since your case is nearing the processing date, they might actually decide to just adjudicate it, stranger things have happened in TSC.
Hope this helped.