Why can't I click on the line?
We're aware of an issue with line selection that makes it extremely difficult if not impossible to click on a line shape that's in a design. Although we're working on a solution, we do want to propose some workarounds to help you resolve this issue.
1. Use the zoom button in the bottom left to zoom in as close as possible to the line and then try clicking on the line. If that doesn't work please contact support