A fix pack for ILOG CPLEX Optimization Studio 12.5 is now available from Fix Central. Specify 'ILOG CPLEX Optimization Studio' in "Product Selector" and "12.5" in "Installed Version" on the "Find Product" tab. Select "Browse for fixes" on the "Identify fixes" page. The download includes a readme listing fixed issues.
Make sure there is an existing 12.5.0 installation and that the fix pack installer has execute permission set before launching. On Windows, run as Administrator and setting Windows 7 compliance when running on Windows 8.