When using the node tool with topological editing enabled on a group of multiple lines, double clicking sometimes doesn't create new vertices. Instead, the line segment gets selected. When this happens, the only solution is to select a different set of lines or a different tool and then return with the node tool to the set of lines I'm currently trying to edit. The issue seems to be aggravated by larger numbers of lines (it doesn't happen at all when editing a single line).
The sequence I run into is I start to edit a group of lines - the first double-click creates a new vertex but subsequent double-clicks result in the impasse and I have to change focus or tools to reset it.
How can I continue to create new vertices by double-clicking?