Branch not appear in gitlab for merge request

Each time our developers commit a new branch to create merge request its not appearing in the gitlab panel .
I searched and debug the issue and i figured out its because of gitlab cache
each time this command solve the problem :
gitlab-rake cache:clear
but I cant do it each time for every branch and for every developer
the question is how can I solve this problem ? how can I make an exception for repositories or completely disabled the caching ?

thank you

any updates for me ?