My smart thermostat resets its schedule every night—anyone else seen this glitch?

I installed a Nest thermostat about two weeks ago to better manage heating in my small apartment, especially since my landlord won’t let me change the baseboard heaters. It works fine during the day, but every morning I wake up to it showing a default schedule instead of the one I painstakingly set up the night before. I’ve tried rebooting it, updating the firmware, and even re-linking my account through the app, but it keeps reverting overnight. I’m hoping to avoid a full factory reset since I’m worried about losing all my preferences and having to re-link other smart devices. Has anyone experienced this kind of nightly schedule reset? What did you do to fix it without starting from scratch?