I am quite new to GIS. I am working on a historical map with three sets of points. When I create a path between those points with the "Points to Path" tool (via Ctrl+Alt+T), it shows up nicely.
However, when I save the map and open it again later, the paths layers are still visible in the layer toolbar, but no longer visible on the map, not even when I click "Zoom to map layer". I am working in QGIS 3.2 (Bonn).
How can I fix this?