I did everything normally, but Vibrato never changes the ringer mode.
Some device manufacturers block the AlarmManager API in a misguided attempt to conserve battery usage. If your device does this, you will need to disable battery optimization for Vibrato in order for it to work correctly. See Don't Kill My App for more information. Once you've done that, reschedule all of your schedules.
How can I reschedule a schedule?
Just change one of the options, and then change it back. I personally prefer to toggle Tuesday twice.
I changed the date on my phone to the wrong day and now none of my Vibrato schedules are working.
Why the heck do people keep—
Never mind. Just reschedule everything.
How do I disable a schedule?
Simply set it so that it never happens — for example, deselecting all days or, if repeat is unchecked, setting the start date before the end date.