If you didn’t know, you can speed up, Headquarters, Mine, and factory at 4:99, for free. You can also up speed up Headquarters and mine when inventory is full, yet you can’t with factory. You have to have space in inventory to speed up factory. So, basically you can’t have inventory full, to speed up factory. So, I’m not sure if TS did this or is it a bug. Either way, this should not be.
Yes, many probably think just keep space in inventory. Well, I like to keep it full, so I can save boxes and prepare for a massive upgrade.
@Sarah247 have this checked out, please. And maybe have this fixed.