Last year, Valve brought the original development team back together for a 20th anniversary Half-Life 2 update. It integrated the post-launch episodes, added a new developer commentary track, brought in Steam Workshop support, and added a heap of map and gameplay updates. All of which was great—except for one progress-blocking bug it introduced to the Entanglement level.
Near the end of Entanglement there's a setpiece where you use turrets to defend Alyx while she resets a teleporter, then jump in with her to escape the waves of Combine soldiers flooding in. Which worked fine, until the anniversary edition. Possibly as a result of said update fixing an existing bug that could make the teleporter leave early, a new bug meant that sometimes you wouldn't be able to enter the teleporter after Alyx—and if you raced to get inside first, she wouldn't follow you.
