I just ran and finished the Bergusia forge at max temper, with a Radiant Sniper Frame in my inventory, and it wasn't completed. No sniper drop, and frame is still in my inventory. The frame is at the step where it tells me to go do the Gofannon Forge ignition. You should be able to forge any frames at Bergusia, unless something has changed? I forged a sniper just last week at Bergusia with no problem.
I'd suggest doing the Gofannon Forge, as per the quest step that's listed specifically on that frame.
Was there anything special about your Run? E.g. you spawned into a running Round, enemies not spawning, anything? Did you deal damage to the Walker Boss? It might happened that the Ignition is not counted if you don't do any damage.