I proposed this theory a while back that their IT systems maybe down, never thought it maybe closer to reality as much.
I saw this post by a user on trackitt, reading which shows that there is great chance above is true, they say they are getting tons of calls from people.
"I called USCIS and the customer rep. clearly told me that they are not going to transfer calls to Tier2 because apparently they have been inundated with calls all day asking them to transfer to tier 2. All she said is she can open an SR which I had already done on July 1. She did look at the details of that SR and tell me that the case has been transferred to a service center but no officer has been assigned to it yet to look at it. I was glad that she was able to give me that information. I think now I am going to wait until July 29 before I call them again. I absolutely felt guilty for calling them and bothering them and/or wasting their time because she kept repeating over and over that they have been getting calls all day asking for transfer to tier 2. I was very polite and she was too but she just kept repeating the same things over and over. I felt sorry for the woman.
Good luck to everyone. I think I am just going to take it easy now and drink my cup of chai

!"