Pagebuilder anchored menu (cannot create sub menu)

Hi here is the situation that a mystery to my.
I've got a pagebulder site with elements organized in stack. Elements lie on each other like cake layers.
utw.fundacjafly.pl/index.php?option=com_...derck&view=page&id=3
I try to create drop down menu where every item of menu will lead to separate anchor point of my "cake".

for exmple
plan is utw.fundacjafly.pl/index.php?option=com_...derck&view=page&id=3

wyklady is utw.fundacjafly.pl/index.php?option=com_...id=3#ID1488285343930

lektoraty is utw.fundacjafly.pl/index.php?option=com_...id=3#ID1488376772556

So far I tried to use Menu --> system links --> external url, but its creates only main menu item eny drop down submenus are invisible (not existing)
I have also used com_blank_3.0.0 which partially does the job.
I can acces my sub menu only afrer i redirect to a blank site that com_blank creates.

if you have any advice I'll appreciate im clueless now

best regards
Kuba

Solved

While creating menu Find and enable show sub menu item, as base menu item create text separator via system links text separator. Now create for example NEW menu . Now create your sub menus as external url like this utw.fundacjafly.pl/index.php?option=com_...d=3#idnumber-or-name . Now attach your newly created link as child item of your NEW text separator. You should get drop down menu that will appear as soon as you roll over NEW menu item

Hi
I don't understand what you are talking about "com_blank", but I see on your website that you managed to do it ?
CEd