I have asked this kind of question recently:
https://forum.dokuwiki.org/thread/10872
But I missed the "folded" plugin. It is reported to be compatible with latest version, strange that it is not working for you.
Quite possible it does not work within the list... Nevertheless, thank you for pointing me to the folded plugin. I am going to try it when I have time.
Update the plugin is working, but not within the list. It is possible to hide whole list, but not the nested part of it.
It is working (whole list is folded):
* ++list1|
* list 2
* list 2.1
* List 2.2
* list 3++
It is not working (even the 'list 3' item is folded):
* list1
* ++list 2 |
* list 2.1
* List 2.2++
* list 3