If one of your readers failing to accept any of your users' mobile keys? If so, it's possible that the reader's bluetooth chip may have come loose. This is especially likely if the reader is still granting access to physical keycards.
Plugged inside every reader is a small rectangular bluetooth chip. This chip is able to identify when a mobile key has been scanned via it's bluetooth signal. Though rare, if a reader is hit with enough force, occasionally the chip can become jostled out of place. When this happens, the reader won't be able to recognize a mobile key scan. Fortunately fixing an out-of-place bluetooth chip is easy! Watch the video below to learn how.