Blizzard has announced that Bullions will continue to drop in the Pre-Patch and the current cap will be fixed.
Bullions will begin dropping again with the next weekly reset, allowing players to get the one they would have missed (the 13th) as catch-up, alongside the regular 14th Bullion. After this reset, Bullion will continue to drop each week until the War Within launches.
Thanks for the reports!.