In the Worker's Day event, you receive event points for upgrading buildings on your base. The amount of points is equal to the base power added with a level up. However, the event registers only those base power points, which are added above your maximum base power. 

Maximum base power is the highest value, which you have ever reached on your base with all the building upgrades you have made. 

If you destroy towers on your base, you lose base power points and your actual base power becomes lower than the maximum achieved. You will not gain points in the Worker's Day event until you raise your base power to the value it was at before the towers were destroyed.

If all buildings on your base are already upgraded to their highest levels, please wait for the future updates of the game, which will add new possibilities for the further development of your base structures.