Motion not being recorded

I've noticed over the last few weeks that my Ring Doorbell is completely ignoring/not capturing movement at random times. First, I noticed there were blocks of time that state "This footage is unavailable" which is not good. Now, it doesn't even say that, just doesn't record. For instance, I left my house around 9:30 p.m. last night to take my partner to the ER, and we returned at 11:30 p.m., and neither were captured. What else was missed? Why might this be?