2X reward card for charging abilities

[Snowfang]

I've had a couple games recently where I purchased the sector 8 2x reward card, and I'm not sure if I'm misunderstanding it's function or if there's a bug.
As I understand it, gaining charge cubes is a reward for activating a sector. The 2x reward card should thus be able to be spent to gain 2 charges instead of one on another sector. The game allows the 2x reward to be activated for sectors with charge cubes rewards, but then doesn't do anything.

[YilanBigfooter]

I've not had that issue myself, I've had success using the 2x card to get 2 rather than 1 cube on another card.

I guess I'd suggest be careful to select the 2x cube before selecting the other card?