I am pretty sure the release notes:
https://github.com/OpenSprinkler/OpenSprinkler-Firmware/releases
mentioned the reduction in the number of programs, because I know this can be of a concern to some of the OS 2.0 to 2.2 owners. You can downgrade to 2.1.6 and import your saved configurations. The newly added features for firmware 2.1.7 did not leave much room for program data, so the number of programs has been reduced.