Are you trying to loop over the same flex field that the repeater=>select is part of. I don’t know if that would cause the problem but I’m guessing that might be it.
My second guess would be that you are not defining the post ID for the have rows loop and ACF does not know what post to use. You can test this by adding the following to the top of your function
global $post;
var_dump($post->ID);
and see what post ACF is assuming it should get the values from.
