I tried the 32-bit and 64-bit versions of MySQL Workbench 6.3 (all my machines are 64-bit machines). Same result. I tried the 64-bit version of Workbench 6.2. Same thing. The newest version that it seems to work with is the 32-bit version of Workbench 6.1 (the only version that's available for download at https://dev.mysql.com/downloads/workbench/6.1.html)
That said, I guess Percona doesn't officially support MySQL Workbench.