Edit: I am on PC BTW. I just found this thread using the search function.
Yes. I am having the same issue, more or less. I started grinding nightwave just before the last weekly reset, and got this far and am stuck now.
I got this Eidolon challenge a couple of days ago which I did not complete as I play solo, and for a while I would get 2 other recovered challenges.
You should have 3 incomplete recovered challenges at a time. However, after several more challenges, I started to receive only 2 at a time, and now I'm getting only this one and nothing more. The set of challenges coming after reset wont be enough to get me to 30, and I'm really worried now that I will be stuck with only this one recovered only. And based on what the OP is saying, even if I go outside of my comfort zone and find 3 people to carry an Eidolon noob to complete it, I still probably wont get additional recovered challenges! 😟
I already had everything from previous nighwaves, and only invested this effort for the umbrals, which will end up being just out of my reach if I don't recover more challenges.