So did I and when I tried to load the save file afterwards, it wouldn't load the save file, but the delete seems to work fine.
After further testing, we seem to have found the issue, although we're not entirely sure about what causes it. The saving framework was not modified for a while, and it worked just fine before this version. The only thing we did that might affect it is we switched this version to the "release" build mode. Previous ones were debug builds.
Perhaps there is an issue with the release build keys required to sign the application for Android. We will look into it further, but for now we're uploading the debug version. Please re-download the app and tell us whether this fixed it for you.