Mouse component - double click

Dear collegues,
Can you help with explaining me what I could do wrong in the following situation:
I have a mouse click component. It ends the routine after I click to valid stimuli.
For the first trial only mouse click words immediately with the first left button press.
However afterwards. when I press mouse button to the valid image, nothing happens. I need to press another one to finally make a response. The same happens in the begining of each routine: firstly “free” mouse click and only after I am able to actually respond.

What the problem can be connected with?

URL of experiment:

Hey @Nikita_Otstavnov, I was unable to access the link you posted, would it be possible to give me developer rights on the project so that I take a closer look? Here to help, thanks, s.

Dear @sotiri, thank you for response!
I think I managed to add you as a developer, amn’t I?
It should be this (another copy):

KO, I’m in, thanks, s.

Dear @sotiri, did you find any idea for solving this bug?
With biggest respect, Nikita O

Hi @Nikita_Otstavnov, could you point me to the exact script that is causing you problems? Thanks, s.

Hi, I’m also having this problem. Did you find a solution?

In the end: yes.
By adding fixation cross prior the stimulus. And you need to click it so that it will disappear.
The second solution was to use keyboard input instead of mouse click