Hey! My fireteam was experiencing a similar issue, and we somehow narrowed it down to the Gunpowder Gamble graphical glitch. The one that has the grenade permanently attached to the Hunter. Did you have a Hunter in your fireteam? If so, that may have been what happened. Some other weird interactions with the tether is that it can't go through barriers, sunspots, and also breaks when the Hunter with the Gunpowder Gamble grenade stuck to them. We fixed it by having the Hunter (me) leave the fireteam and rejoin. I was able to do that since I already had Divinity, otherwise my progress would have been reset, so watch out for that. Hope this helps!