I made a few macros today with the latest version of the FF addon, i haven't experienced any issue. It saved them just fine and i can play them as usual.
But what's the exact case here? It just went poof from one day to another with you doing nothing? Are you sure that the folder path which is set in iMacros is actually the correct path of the macros folder? Maybe you moved something and it's not in the default place anymore, so the addon cannot load/save the macros.
You can check the folders under Manage/Settings/Paths.