after it happened to me in at least one Solo Challenge in the 'Team Standouts: Serie 3' promo yesterday, I took notes, how often the bug happens to me in this promo.
yesterday, I had the bug twice (one after 6 games in a row (or earlier), and one after 5 games). today, I did not face the bug while playing about 20 solo challenges.
in detail:
yesterday, I played the first Solo Challenges in a row (i.e. always started the next challenge immediately after completing the previous one without going back to the menu) and realised the bug in the Solo against the Chargers. so, at least the 8th challenge was affected.
after completing this challenge, I went back to the menu and started the Solo against the Chiefs from there. Abilities and x-factors were there for 5 Solos, but they were gone in the 6th against the Falcons.
Today, I started with the Solo against the 49ers and completed 13 challenges in a row (the last one was against the Saints). in all these challenges abilities and x-factors were there. I also tried to repeat a challenge (after completing it) to test whether repeating the challenge triggers the bug. it did not.
after that I repeated the solo against the 49ers and went back to the menu, tried to sell some items from the item binder.
in my next 2 games (against Seahawks and Steelers), the bug did not occur either. it also did not occur in the remaining 3 challenges which I played after checking my lineup