the issue is caused by bad logic of data update, see RestconfStrategy insertWithPoint{Put,Post}

insertion of a new item is performed while iterating through existing elements,
if the index of new item is greater then the list size (insert after last item)
then insert condition condition is never met and actual insert is omitted.

also the update logic seems being not effective, all the list items are being 
rewritten one by one using tx.replace(), it seems reasonable to update the data
via whole list replacement not item after item. At least start from affected index.