Mercedes Sheldon and Lv25-29 tier arcs
I am not looking at the wiki or anything, but I know when I was combing through missions some missions appear later in Ouro then they do on the contacts. It's possible the arc in question is one.
Also I know that I've gotten souvenir in mission arcs I've "Failed" a few red side ones are different if you succeed or not.
Thanks for the info. I was wondering why she suddenly stopped talking to my late 20s scrapper as well.
Her arcs don't go the full range.
If you run them in flashback you get dropped to level 25, so they are more 20-25 arcs than 25-29 ones.
On the plus side, every mission she has in accessible via flashback.

@Catwhoorg "Rule of Three - Finale" Arc# 1984
@Mr Falkland Islands"A Nation Goes Rogue" Arc# 2369 "Toasters and Pop Tarts" Arc#116617
Hmm. Flashbacking to the second arc does knock you back down to Lv25, despite what the crystal says - the Wiki apparently already has this bug documented. On the other hand, what about Skippy? Will I have to run his entire arc again for a chance to get the souvenir?
Bit of weirdness here - I just finished Mercedes' first arc, the Dirge of Chaos. Now, being solidly Lv29 thanks to the XP handbrake, I was ever so slightly surprised by the sudden stop after the arc was completed. The Magic Man arc... isn't. She just tells me to bugoff.
So, I drop a portal and swing by Ouroboros to see what level range the arcs are, exactly. And... they're Lv25-29. And listed and available for my Lv29 character, along with all other arcs in that range.
What. The hell?
Edit; also, is it normal not to have an arc flag as complete, souvenir and all, if you fail the last mission? Referring to Skippy's infamous 30 arc.