A very serius problem for me occurs when I control group: only one building ques production and the rest do not que anything. For example Ctrl+1 for three TCs should que one villager each but only one TC ques all threen villagers while the other two are idle.I have tried using different keys for groups.

PS: This occurs recurrently and not everytime I play.

This will only happen when the host of your game room starts a game with SQ instead of MQ. To avoid this, make sure the host has the game settings set to Multi Queue (MQ) before you click 'I am ready'

I am sure it was MQ, but the problem is rare so i dont mind.

Indeed it's rare as there are very few people who still play with SQ set as default. The rare instances you are referring to are the ones where the host started the game with SQ and no one noticed it. There is no other reason.

Just be careful every single time and you won't have this issue ever.