Yam Network upgrade bug

Sometimes when you go for Silver Tree landmark on Mongols, upgrading Yam Network doesn’t work (even after you upgrade it, the Yam Network upgrade button still exists and is still selectable on outposts). I have replicated this bug multiple times, both on the ladder as well as in skirmishes.

Thank you for bringing this up @ElmoKajaky! I’ll have the team check it out.