I capture the great library along with other wonders from the evil Japanese in GOTM #5. After over 100 turns I still havn't reaped any new techs.... and several techs have 2 or more owners. I have the latest patch 1.17. The other wonders are behaving correctly.

As it states in the manual, captured wonders do not work for you, it will only work again once the original owner capture it back. also the great library is obsolete after education is discovered.

A captured wonder's effects should work for you. It is the culture from the wonder that you don't get.

Like MoonDragon mentioned, it's most likely that Education was already discovered rendering the GL obsolete no matter who posessed it.