Shipping zone/Limit to specific postcodes not saving

Hello and thank you for all your help so far!

I am trying to save a shipping zone in Woo Commerce with around 29 000 postcodes entered in the “Limit to specific Zip /postcodes” box found in the Woo Commerce “Add a shipping zone” interface. All the postcodes are pasted successfully however when I try to save the shipping zone, it gets stuck in saving.

When I try to save the same shipping zone with about 10 000 zip codes the information gets saved instantly.
I did some research online and found out this could be a server issue:

“If you notice product variations, tax rates and other large data sets not saving, Suhosin (a security module in PHP) may be preventing the POST data from being saved. This issue can also be caused by servers with version PHP 5.3.9+ and servers running mod_security.”

Could you please confirm this is not a Woo Commerce issue before I have my hosting provider look into it.

Thanks
Vassilio