Ace by Daisy reports an invalid serious error about page-source

[jhswift]

InDesign V20.0 (to be released in 2 weeks time) now including a correctly formatted item for the page-source of an ebook with page-lists.
The format is :
urn:isbn:9781681727738
But ACE is still reporting this as an error. It still expects the (now deprecated?)
<dc:source id="src">urn:isbn:9781681727738</dc:source>