So I found out that while opening the project and it complain about missing files.. the uncheck file extension is not working –it will not find the other files.
What I did :
Klik offline all.. and let the project open.
Once it open, I select all the offlines and click relink..
The same offline/relink dialog box open.
But this time I can uncheck the extension and it will relink all the rest (with different extension) as expected.