I was waiting until a new Gem event happened it said 4 minutes on the count down. Then when it reached that the icon just disappeared. Is this happening to everyone or is it just me?

Was it between the end of a monthly challenge and the beginning of the new one? If so there usually is a gap between the two themes. Also the 4 minutes is just how many minutes are left with the current one. It shows how many minutes before it is over so you can collect your prizes. If this wasn't the case, then ignore my answer.