I tested that, while units stay in formation as they walk, they still break formation when they attack. It would be nice if they rigidly kept at least the Phalanx, as that’s more historically accurate than walking in the phalanx and then breaking formation.

I used chrome browser (instead of brave) to download the version 28 executable. I installed version 28 over version 27.1, without uninstalling version 27.1, now version 28 works. I don't understand why, but now it works. LOOOL   Thank you very much ALL. Let's play !! 

Same errors .    

It's buggy but there is a setting for this to happen. Options > Game Session > Formation control > No override

Agree - but with the additional question (option to keep existing configs etc.) this would be just perfect.