There's a fair bit of backstory to this issue, so there's a lot to mention.
Yes, this has happened to me on a few occasions when running it. It's the macrobinocular mission series finale, which was meant to be a heroic 4 mission (but it can be 3-manned with phasewalk and the sniper's equivalent). I believe it's called "The Shroud's Last Stand" on impside. On pubside, the equivalent mission is called "The Shroud Revealed." The mission that precedes this one in the chain is my absolute favourite in the game
The fight mentioned is the finale mission's first boss encounter, where players fight a few waves of droids and turrets on a floor with an array of mines that periodically activate on a rotating basis, forcing melee players to have to move around while fighting in order to avoid being hit and stunned by the mines (ranged can stand back on a mine-less platform at the back of the room and maintain full uptime).
A year or two ago, the game implemented a change to ranged mob pathing because ranged companions wouldn't follow players around in combat, causing them to stay stuck out of range. This has changed many fights in the game, like Thrasher in the Scum and Villainy operation, because ranged enemies had started moving when they're not supposed to. This happens to Draxus in Dread Fortress as well.
The reason why it's a problem here is that there's an energy shield around the controller droid in the middle of the mined floor. It serves as a physical barrier that players can't move or get line of sight through because killing the controller ends the encounter. This barrier isn't an obstacle for enemies however, so the ranged enemies often accidentally move inside the shield while pathing to players (especially if the players are ranged and standing on the platform) after the ranged mob pathing change from the last paragraph. Every droid in a wave must die to cause the next wave to spawn, so if one gets trapped in there, players have no way to hit it or force it to move out because the shield blocks line of sight. Even AoE abilities can't reach an enemy stuck in there.
The workaround that one of my recent groups found is to make sure to make the droids not path through the shield, or to have each player aggro a separate one and keep it in melee range so that it doesn't move. Given that this content is sadly barely played because it requires a group (part of what makes it fun and unique) and that the problem has a workaround, I wouldn't expect this to get fixed. The ranged companion pathing bug took months to get addressed, and it seems like the implemented fix was a fundamental change to the game's foundations.