Oneflow will log you out automatically after a set amount of time. This is a security measure to make sure no one can access your account in case you forget to log out, your device is stolen etc.
However, if you click the checkbox marked "Keep me logged in on this device" the time before you're logged out will be increased to 2 hours.
But I wasn't inactive, I was in the middle of editing a template/contract!
Working in our editor doesn't register as activity, as no updates are made. To prevent being logged out, and a good rule in general, remember to save your edits frequently!