two groups of units cannot be directed

Thank you for your report.

This is a known issue and is currently being worked on by the developers.

We do understand your frustration. Bugs can be difficult to correct, but please know we are doing or best to make the game bug free.

We call this bug the Bermuda Triangle, even though it is in the pacific. It has to do with the map seam. Units within the map seam may not be clickable.

PS: Workaround: The units can be selected by cycling through the units with the left and right arrow keys until the desired unit is found.

Or of course by using Ctrl F and searching for the unit designation. I suggest keeping track of unit designations for all units operating near the map seam.

An additional workaround is to hold the right mouse button and circle around the area. In the case of planes you have to circle around the airbase they are based from.

This map seam runs all the way north to south at that longitude.