I spent 3 days grinding for a third Enduring Legacy so I can upgrade mine further. When I used the Weapon Station to upgrade the unique abilities the donor weapon was consumed. I was presented with a completion notice, but my current weapon only had one upgrade. It should have 2.

I have seen this happen before on a earlier weapon. I believe this is random but this should not happen at all. Grinding out top tier weapons takes significant time and effort. It is bad enough I need to collect enough to build 5 of each weapon. Now I need to collect 6 or 7 times to get 4 upgrades?