Hi Jessica! Welcome to the Disney Parks Moms Panel!
You've hit upon one of my favorite ways to pass the time between Walt Disney World visits. Checking wait times in the My Disney Experience mobile app and dreaming of Disney days to come is almost like being in the Theme Parks themselves. My 5-year-old son even gets into the act, checking the times and announcing them to us on a regular basis.
When I'm in the Parks, I've found that the wait times are pretty accurate. On occasion, though, you'll find a star where you'd expect the wait time to be. I haven't seen an official explanation, but what I've observed personally is that the stars can mean a few things. First, most of the shows that run on a schedule, like Finding Nemo: The Musical or Mickey's Philharmagic, will usually just show a star instead of a wait time since they run on a schedule. Also, many attractions like the Tomorrowland Transit Authority Peoplemover that continuously load Guests throughout the day will not post wait times.
Sometimes you'll see a star next to an attraction that does normally post wait times. When that happens, you can try to refresh your app and see if the times come up again. If that doesn't work, it may be that the wait times aren't reporting correctly because the attraction has shut down temporarily or there's been some technical glitch. The correct wait times should load again shortly.
Again, this isn't an official explanation, just my own experience. I hope it helps you have fun following the fun of a Disney day, Jessica. Please stop by and see us again if you have any more questions.
Keep Disney Dreaming,
Kathy K.