checkout shipping fails when reloading

[dmitspan]

Hi,

 

I have several installations of OSC 2.2 using sts among different servers and different shipping modules.

 

When I go to checkout shipping for first time everything displays fine, I choose the module and continue to payment.

 

But if I go back to shipping either by browser's back button or by a link most of the times the shipping modules disappear and I must hit F5 (refresh) button to see them all.

 

Is there any hit why this happens?

 

Thanks