A new update for BlastZone 2 has been released that improves SteamCloud support for the game. Now, only local high scores and unlock progress are saved in the cloud. All per-machine settings such as resolution, details, and controls are no longer saved in the cloud.
Migrating your unlock progress to the new system is simple. Just start up BlastZone 2 using the machine that has most recently been used to play the game before the update. Using a machine with less progress won't harm the process though, as the older progress will automatically be overwritten by any machine with more progress.
To make sure you have the latest update, the version is v1.12.7.5
Enjoy!