Tcode Open for processing Even with Closed Client.

Hello Experts

I have a query. We frequently used to create CITY codes earlier using Tcode OVKG earlier directly in production system even when

the client was closed for processing.

Now from a few days , we are finding the tcode is non-editable and we have to create the city code in Dev system and move it to production .

Can somebody tell me what changes are done at the backend to facilitate this and how could this be reverted.

Thanks in advance.

Ranjan