This seems to be similar to two other issues reported earlier:
This time I noticed that an existing connection via link nodes between two flows broke so I checked what goes wrong. When I clicked on the link in node, the editor did not show visually a connection which was listed when I opened the link in node configuration:
After simply hitting the done button in the configuration, the "lost" connection (init-resync) appeared:
Deployed this "change" and the connection between the two flow started to work again. Does anyone have any hint on why this happens? This seems just as mysterious as the other disappearing wiring issues.