A display of “-1” instead of a cycle day means that this day is not assigned to any cycle.
This can be due to various reasons (such as the absence of a period entry in the app). Please contact us, so that we can take a closer look at your individual case (email@example.com).
Please either provide your sensor ID (to be found in the yellow tab of your app) or with a photo of the bottom of your white trackle storage box (there you can find the long serial number).
We will be happy to help you.