Editing text adobe illustrator files from china

I am working with a packaging manufacturer in China. I create the files using .ai cs6 but after they make adjustments to my files and send the file back to me, I can't edit the text like I normally would using the cursor.

The Selection Tool (V) and The Direct Selection Tool (A) allow me to select a letters or words like an object. I can insert the cursor as if it looks like I will be able to edit the word or sentence normally but the cursor just blinks and or doesn't move when I type.a

Does anyone know why this happens and how I can fix it?

Also, when sending files to places like china, should I be saving the .ai with a certain setting?

Any help is appreciated.