I feel like i might be a little paranoid, but occasionally, when changing an existing connection the new connection is not saved properly and after reopening the blueprint, you'll have the old connection.
This has happened in the past but I couldn't ever be sure if it's maybe just my memory failing me. but now I've finally seen it in action. Hard to show though since it worked on the third try.
Seems to only happen with bigger blueprints and not with new connections but only with replacing connections.