Hi Ange,
Unfortunately this is an issue with the new update for the Community. It's all a bit technical and if we were to solve this, it would log everyone out after being logged in for an hour regardless of whether you can log out or not. The obvious issue is that this will affect everybody on the Community - even those who are not experiencing this problem.
We are currently looking to find an alternative solution, but as this is an issue cause by the core of old system and the core of the new system it could take some time. Please bare with us whilst we try to find a solution.
Apologies for the inconvenience.
Kindest regards,
Monty