Why can't I activate my hyper EXP stones?
You can pause your hyper EXP only ten times in a row. After the tenth time you paused it, you cannot activate any session (Hyper EXP time, Buffer time, or Exhaustion time) or put in a new stone. You have to wait until 24 hours after the moment you paused for the 10th time before your full 10 pauses reset.
For example, if you started off a hyper at 09:00 on Monday, and paused for the last (the tenth) time at 13:00, you can't just start it up at 00:00 server time that night. You have to wait until 13:00 on Tuesday to be able to use hyper EXP sessions again or put in a new stone.