Running into problems is only to be expected when running alpha-builds...
To work correctly, both server-side and client-side must be upgraded, and very few projects has yet upgraded server-side so don't work at all with 64-bit-clients. But, even if server-side upgraded, even the last alpha-build, v5.9.9, is still buggy, and don't work correctly with all upgraded projects...
Hopefully v5.9.10 fixes this, but afterall it's alpha, and has also various other bugs...