Rails which have controlling logic connected (e.g. to change the rail direction) are not shown as connected (slaved) to the logic after use. This applies to the purple highlighting as well as the action tooltip ["Connect Button to Rail Basic ('V')"]. The mechanism continues to work so is presumably still connected server-side, but the highlighting and action are wrong as seen by the user.
Performing the currently shown action is consistent with the result; pressing V at this point highlights the rail(s) in purple and the mechanism continues to work. Pressing V again disconnects them. But upon use it "appears" disconnected again. Unless the user knows what rails were supposed to be connected to the button it is not possible to troubleshoot/repair the setup. Reloading the game (single player) results in showing the links as expected again.