also I found something that might lead us to a solution. If I create the same mapkey but instead of a leader note, I use a Balloon Note, it works just fine.
and changing the min and max size of balloons is not an option; well for this situation.
thank you for all the help so far!
mapkey y @MAPKEY_NAMEBALLOON;@MAPKEY_LABELBALLOON;\
mapkey(continued) ~ Activate `main_dlg_cur` `page_Annotate_control_btn` 1;\
mapkey(continued) ~ Command `ProCmdDwgCreateBallon` ;#MAKE NOTE;#ARROW HEAD;\
mapkey(continued) @PAUSE_FOR_SCREEN_PICK;@PAUSE_FOR_SCREEN_PICK;&piecemark:att;;#DONE/RETURN;