F5 did not solve the problem.
Tried several times - same problem each time.
Tried again on a subsequent move - same problem.

It gets past the pay combat card step, and then fails at the point you try to choose the resources .

Exact steps:

1. Click on Factory Card
2. Click on Pay 1 card, Gain 3 resources
3. "You must choose how to pay 1 card" - click on a card, click on Confirm
4. "You must choose how to gain 3 resources"
5. Click on food - it now shows 1 food and the cancel button correctly becomes enabled
6. Click on metal - it now shows 1 metal
7. Click on metal again - it now shows 2 metal and the resource buttons grey out. BUT the Confirm button has not become enabled. Only enabled buttons now are Cancel, Undo or Restart Turn. So cannot progress beyond this point to actually take the resources.
8. If I click on the greyed out Confirm button to try to confirm and take them, I get "Unexpected error: Invalid hex. Should not happen (reference: GS13 26/07 12:24:52)"
9. If I click on the greyed out resource buttons - say metal again - it increments to 3 metal. If I repeat that it keeps adding another and another and another.

Without the Confirm button becoming active and working, there doesn't seem to be a way to use this card at all.

Just to check:

Did you make sure to choose a territory for each resource? It should work the same as the trade action. The steps should be:

1. Click on Factory Card
2. Click on Pay 1 card, Gain 3 resources
3. "You must choose how to pay 1 card" - click on a card, click on Confirm
4. "You must choose how to gain 3 resources"
5. Click on food - it now shows 1 food
6. Click on a territory
7. Click on metal - it now shows 1 metal
8. Click on a territory
9. Click on metal again
10. Click on a territory
11. Confirm

Thanks for the info. No, I didn't choose a territory for each resource - it didn't prompt me to do so, so it wasn't clear that was what I was supposed to do.

I've just tried it with selecting the territories (the game is still ongoing) and that works OK, so that card is now usable for our game - thanks. It could do with some better instructions and stopping you from selecting multiple resources without selecting territories in order to improve the functioning of this card.

Similar happened to me with this card, except the confirm button never became active and an error banner popped up

Same issue today. The "problem" is simply, that there is no "pick a territory" prompt. Maybe the developers could add something in that regard.

I'm not sure about the official rules. Do the resources have to be put in the same territory? If not, there's a bug report about it already.

Anyways, the solution here is to click on a controlled hex. Then you can get any 3 resources.