I was reading ISO 8601 wiki:
And found out:
"Representations can be done in one of two formats – a basic format with a minimal number of separators or an extended format with separators added to enhance human readability."
But if I use ISO8601 date filter for the following, I get a "_dateparsefailure":
For me it looks exactly as basic format of ISO8601.
I didn't find any discussion on this topic in the internet, so decided to start one here.