The measurements you create are using an incorrect scale or measurement unit.
This happens because the document contains at least one Viewport which defines the scale and units of measurement.
You can remove the unwanted viewport by following these steps:
- Open the Measurements (Alt+U) panel and expand the Viewports dropdown.
- In the Viewports list, click to highlight the viewport you want to delete.
- Click the Clear All Viewports icon .
- Select Clear All From Page to delete the highlighted viewport from the current page;
Select Clear All From Document to remove viewports from the entire document.