I'm 50-50% divided between believing *it's a tech glitch and *they're working on your file. :-\
The system should still recognise you even if they're working on your file. Also, it is happening randomly with applicants in different stages of processing - hence tech glitch. You can see this very same thing has happened in the past as well if you look at some of the past discussions here.
While on the other hand, I've experienced it myself recently that my address disappeared and I received request for updated sch.1 after it reappeared. So they could be working on your file. However, the difference is that the whole E-cas is gone, not just the address!!!
Nevertheless, here are my timelines & stats:
NOC - 1122
VO - London
App sent - Sept 2010
1st AOR - Jan 2011
In process - July 2011
Med & RPRF Req - 14 May 2012
Med & RPRF recvd - 7 June 2012 (tracked courier)
E-Cas disappeared - (around) 10 June 2012
Anyone else in similar stages and with this occurance?
Has your E-cas returned yet? If 'yes', any change in status or notification?
Good luck guys!