Geoff, thanks.
Similar experiences with cookies, some success, but not those ads within this particular app.
Reset everything I could find.
Many leads to Google ad manager, all ad links turned off. Greater success; only adds from NS ‘to be come a subscriber’, which of course because I was already using the app !!!
Overnight some Google adds reset them selves and now reappear.
The issue appears related to Behavioural Advertising and Google ad manager, and only the NS app - still waiting for their reply.
What more might be done ?