Stopped redirecting to the PAYU page

Hi all,

We are using Payments.MonoPayU v1.4 in Busrapirlanta.com.tr (NopCommerce v3.8). It has been working successfully however it stopped working in the last few days.

The payment page seems to direct to PayU however that page does not open, it waits with a white empty screen and then goes back to busrapirlanta site and says the payment was successful. Screen capture video here:
https://drive.google.com/file/d/0ByJ1w52NmcDEckJvb2VRaGNzVUU/view?usp=sharing

Could you please help what could be happening here?

PS: I got in touch with PayU but they say transactions are not reaching to their side at all.

Thanks!

This was apparently due to the language settings; we had switched to Turkish and that was not handled well for some reason. Now we switched back to en-US and it works.