Nu-HTML checker - <details> as child of <figure>?

Hi:

I would like to use <details> as a child of <figure> but get an error
message when running the Nu-HTML checker.

error: Element “details” not allowed as child of element “figure” in this
context. (Suppressing further errors from this subtree.)

I believe my use of <details> as a child of <figure> is flagged because I
am also using <figcaption> within the same <figure>. When <details> is a
child of <figcaption> within the <figure>, the error goes away.

I also noticed that when I use <details> as a child of <figure> that does
not have <figcaption>, there is no error.

I am wondering why the Nu_HTML validator allows <details>1) as a child of
<figcaption> and 2) as a child of <figure> when there is no <figcaption>,
but not 3) as a child of <figure>, which also has <figcaption>.

Note: I have tested <details> as a child of <figure> with a <figcaption>
with Firefox, Chrome, and Edge and noticed that these browsers do support
this combination.

Thanks for your help,

Joseph


-- 
*Alternate Media Supervisor*
Disabled Students' Program
University of California, Berkeley
https://dsp.berkeley.edu/
<https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdsp.berkeley.edu%2F&data=02%7C01%7C%7C4e0abffcb5b34567a22308d5e13137b3%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636662523854357148&sdata=yB5%2BUm2W6TBwpc%2BOF4DvN8wPoo1dozUwz8eCepYhTyY%3D&reserved=0>
(510) 642-0329