I have the same bug. I managed to progress by picking up the fallen soldiers' assault class and using the beacon from their loadout. However, even after I fully completed the assault path, the beacon is still unavailable. Additionally, when I click on the assault class badge, it indicates that I still have one challenge left to complete, even though all have been completed. This whole thing happened when the requirements for challenges were lowered, and on the previous requirements for assault 1 challenge wasn't completed, but based on the new requirements, it got "auto complete", but the beacon was not unlocked.
