Read on below to learn more about a Pokémon Sleep bug notice:

Thank you for playing Pokémon Sleep!
The game is currently experiencing the following issues.
Bug Areas
Sleep tracking
Bug Contents
A feature can’t be used.
(Occurs under certain conditions.)
Work-Around
Update
This can be dealt with by navigating to the MENU from the title screen and selecting Clear Cache.
Status
Update
This is scheduled to be released in a future update.
The following gift will be sent at a later date to the Gift Boxes of players who were affected by this issue.
• Contents
Poké Biscuit ×3
Sleep point ×100
We sincerely apologize for the inconvenience caused.
We hope you continue to enjoy Pokémon Sleep!
Source: Official Pokémon Sleep news
Source: Pokemon