This is a self-contained example that demonstrates that hovering on edges does not reset the edge style color to its default values. Hover does work correctly on nodes, although the update times are slow.
To replicate, download the files, start a server, I use:
http-server
from within the folder that contains index.html and index.js, the only two files reqired.
Then type localhost:8080 in a browser. This will load up index.html.
Hover over the nodes and edges.
Nodes turn red and return to their default color.
However, Edges change color on hover, but do not return to their default state.
Is there a bug? How do we fix this?