3rd level menu appear as parent menu

[AhmedFaisal]

self explanatory enough
the menu is structured that way:
menuitem 01
--subitem 011
menuitem 02

• subitem 022
  -- sub subitem 0222
  well. it looks like this:
  menuitem 01
  --subitem 011
  menuitem 02
• subitem 022
  sub subitem 0222 ==> same level with menuitem 01
  after googling it turn out to be a bootstrap navbar issue and it said it can't support mor than 2 levels menu, but also many bootstrap based menu has fixed that issie. please make a fix too.