Error using cvx/times: Invalid quadratic form(s): product is not real

Dear,
I try to solve my convex problem but it has an error “Invalid quadratic form(s): product is not real”.
I found no explanation about this error in the internet.
Could you help me explain why we have this error? Is there any sample codes for this error? How to fix it also?

Thanks so much,
My code is so complex to view so I don’t put it here.

https://searchcode.com/codesearch/view/2493713/