Mongols. Control group is lost when packing buildings; packed buildings will only stay in the control group. Unable to create a control group with both packed and unpacked buildings.
I noticed this bug yesterday and was going to report it today but can see you have already reported it.
Packing one building up will keep that building in the control group and remove all other buildings from the control group.
I don’t know if they fixed it in this latest patch, but this happened to me a few days ago and I was quite frustrated and not understanding why. I will test if it is working properly now.
Thank you for reporting again @cienlo! This is one we are aware of but have not yet time to tackle. It is on the list, though!