Question is similar to this: How to debug a Symfony2 form?
The problem is - on posting data - the data is in $_POST array. Form has the fields and they even have some values.
After handleRequest - those values become nulls.
The form is big, its a lot of work now to minimize the code. I think other developers know where else to look for to see the problem.
I have tried looking in debug bar, but I don't see anything useful - just errors, one of them that field is not filled which is not true because it is in $_POST array.
Stepping inside handleRequest also sounds unproductive with many of those loops going on there and unclear code inside.
I have a problem with Symfony 3.4.