Microsoft App Updates (via MS Store) Trigger NS Firewall Warnings

For a couple of months now Norton FW has been flagging updates of Microsoft Apps (pushed by the Win-10 Store) as having invalid digital signatures...

Today was no exception - the Store pushed in several Microsoft App updates:

3.jpgAnd within minutes the Norton FW was alerting to Signature problems with the new Apps...

1.jpgThe only apparent meaningful detail for the offending Apps being their relative newness ...

2.jpgSo what offending "Digital Signature" is being referred to here?

FWIW, this is happening on all of my Windows-10 systems as well as those of friends running Windows-10 systems and also having NS installed.

Thanks