TYPO3 doesn't show any pages in submenu

In my TYPO3 I have this code for submenu

lib.subnav = COA
lib.subnav {
wrap = <ul class="nav nav-list" id="sidebar-nav">|</ul>
10 = TEXT
10.wrap = <li class="list-group-item">|</li>
#10.wrap {
#    override = <li class="list-group-item current">|</li>
#    override.if {
#        value.data = field:uid
#        equals.data = leveluid:1
#    }
#}
10.data = leveltitle:1
#10.data =  levelfield:1,nav_title // leveltitle:1
10.typolink.parameter.data = leveluid:1
20 = HMENU
20.wrap = |
20 {
entryLevel = 1
1 = TMENU
1 {
wrap = |
expAll = 0
NO = 1
NO.allWrap >
NO.wrapItemAndSub = <li class="list-group-item">|</li>
CUR = 1
CUR < .NO
CUR.wrapItemAndSub = <li class="list-group-item active current">|</li>
ACT = 1
ACT < .CUR
ACT.wrapItemAndSub = <li class="list-group-item active">|</li>
# Dropdown menu
IFSUB = 1
IFSUB < .NO
IFSUB.wrapItemAndSub = <li class="list-group-item">|</li>
IFSUB.ATagBeforeWrap = 1
IFSUB.stdWrap.wrap = |
CURIFSUB = 1
CURIFSUB < .IFSUB
CURIFSUB.wrapItemAndSub = <li class="list-group-item active current">|</li>
ACTIFSUB = 1
ACTIFSUB < .IFSUB
ACTIFSUB.wrapItemAndSub = <li class="list-group-item active">|</li>
}
2 = TMENU
2 {
wrap = <ul class="list-group">|</ul>
expAll = 0
NO = 1
NO.allWrap >
NO.wrapItemAndSub = <li class="list-group-item">|</li>
ACT = 1
ACT < .NO
ACT.wrapItemAndSub = <li class="list-group-item active">|</li>
CUR = 1
CUR < .ACT
CUR.wrapItemAndSub = <li class="list-group-item active current">|</li>
IFUSB < .1.IFSUB
ACTIFSUB < .1.ACTIFSUB
CURIFSUB < .1.CURIFSUB
SPC = 1
SPC.doNotLinkIt = 1
SPC.doNotShowLink = 1
SPC.allWrap = <li class="divider"></li>
}
3 < .2
# no submenus anymore
3.IFSUB >
3.ACTIFSUB >
}
}

If I wiev the source of the page I can se this line: <ul class="nav nav-list" id="sidebar-nav">|</ul> but no menu items.
I have tried to chage submenu.entrylevel, but nothing changes.
There a subpages, so that is not the problem.

It is TYPO3 8.7 and I know that it is terrible old, but I need this to work before an update.

Let's have an example page:

• Home/Root
  • Page 1
    • Page 1.1
      • Page 1.1.1
    • Page 1.2
  • Page 2
  • Page 3
    • Page 3.1
    • Page 3.2
      • Page 3.2.1

Regarding entryLevel:

Default is "0" which gives us a menu of the very first pages on the site. For the tree above, the menu will contain "Page 1", "Page 2", "Page 3".

entryLevel=1 will show the pages below. So, if you are on "Page 1", the menu will show "Page 1.1." and "Page 1.2" (active rootline). On "Page 2" the menu will not show up anything, because there are no pages below Page 2. On "Home/Root" no menu will appear because there's no level 1 directly underneath.

expAll

If this is true, the menu will always show the menu on the level underneath the menu item.

Back to the pagetree: having entryLevel=0 and 20.1.expAll=1 all submenus of the third level will be expanded, not only the one of active rootline. All "Page x.x" will appear, but none of the "Page x.x.x".

For getting a full dropdown-menu, also the next level needs to be expanded: 20.2.expAll=1