Soft-locked in Oblation

Hi guardians! I've done the first two missions of Oblation (bloodline and soulfed, I believe are their names). But at the end of the second one, I couldn't continue as the game simply ended the activity and gave me loot. As a result, I only have access to the first two missions and I cannot find a way to get access to the last bit.

I've tried the following already:

* Starting Soulfed from the node in the Moon and activating the switch in the middle of the mission (there's only one switch right?), nothing happened.

* Landing in the Sorrow's Harbor and then starting the mission from scratch. This results in the mission ending after the very first boss.

I've tried these multiple times, also tried not activating the switch in the second mission just in case, to no luck.

What am I missing to be able to play the last third of this mission?