Hi,
Same happened with me after receiving SA on July 7th, it went to in process and after that changed to application received.
During all that time i was checking ECAS status using UCI and for some reason today I checked ECAS status using Application number to find out that there is an update on ECAS saying that they sent a correspondence on July 15th, we have not received anything till this date.
Other great users informed me that most likely is the request for photographs for which they received requests back in July.
Please make sure to check status on your ECAS using your application number and make sure you click the link for application received to read any status update.
Also could you let us know which visa office your application been forwarded?
Thank you