Alphavantage intermittently failing to return ASX quotes

[prl]

I'm having problems this morning (3 Dec 11:30 Eastern Australian Summer 
time, 3 Dec 00:30 UTC) with Alphavantage intermittently failing to 
return quotes for the four ASX (Australian Stock Exchange) stocks that 
we hold:

gnc-fq-dump -v alphavantage CBA.AX IAG.AX QAN.AX TLS.AX
Finance::Quote fields Gnucash uses:
     symbol: CBA.AX               <=== required
       date: 11/30/2017           <=== recommended
   currency: AUD                  <=== required
       last: 79.1700              <=\
        nav:                      <=== one of these
      price:                      <=/
   timezone:                      <=== optional

All fields returned by Finance::Quote for stock CBA.AX

stock           field  value
-----           -----  -----
CBA.AX          close: 79.1700
CBA.AX       currency: AUD
CBA.AX     currency_set_by_fq: 1
CBA.AX           date: 11/30/2017
CBA.AX           high: 79.9500
CBA.AX        isodate: 2017-11-30
CBA.AX           last: 79.1700
CBA.AX            low: 78.8800
CBA.AX         method: alphavantage
CBA.AX           open: 79.7100
CBA.AX        success: 1
CBA.AX         symbol: CBA.AX
CBA.AX         volume: 2462019

=====

Finance::Quote fields Gnucash uses:
     symbol: IAG.AX               <=== required
       date: 11/30/2017           <=== recommended
   currency: AUD                  <=== required
       last: 7.1200               <=\
        nav:                      <=== one of these
      price:                      <=/
   timezone:                      <=== optional

All fields returned by Finance::Quote for stock IAG.AX

stock           field  value
-----           -----  -----
IAG.AX          close: 7.1200
IAG.AX       currency: AUD
IAG.AX     currency_set_by_fq: 1
IAG.AX           date: 11/30/2017
IAG.AX           high: 7.2200
IAG.AX        isodate: 2017-11-30
IAG.AX           last: 7.1200
IAG.AX            low: 7.1050
IAG.AX         method: alphavantage
IAG.AX           open: 7.2000
IAG.AX        success: 1
IAG.AX         symbol: IAG.AX
IAG.AX         volume: 3320131

=====


Finance::Quote fields Gnucash uses:
     symbol: QAN.AX (deduced)     <=== required
       date: ** missing **        <=== recommended
   currency: ** missing **        <=== required
       last:                      <=\
        nav:                      <=== one of these
      price:                      <=/
   timezone:                      <=== optional

** This stock quote cannot be used by GnuCash!


All fields returned by Finance::Quote for stock QAN.AX

stock           field  value
-----           -----  -----
QAN.AX       errormsg: json_data doesn't contain Last Refreshed
QAN.AX           last: **missing**
QAN.AX            nav: **missing**
QAN.AX          price: **missing**
QAN.AX        success: 0

=====


Finance::Quote fields Gnucash uses:
     symbol: TLS.AX (deduced)     <=== required
       date: ** missing **        <=== recommended
   currency: ** missing **        <=== required
       last:                      <=\
        nav:                      <=== one of these
      price:                      <=/
   timezone:                      <=== optional

** This stock quote cannot be used by GnuCash!


All fields returned by Finance::Quote for stock TLS.AX

stock           field  value
-----           -----  -----
TLS.AX       errormsg: json_data doesn't contain Last Refreshed
TLS.AX           last: **missing**
TLS.AX            nav: **missing**
TLS.AX          price: **missing**
TLS.AX        success: 0

It's not always the same stocks that fail. Occasionally I get them all.

Is anyone else seeing this sort of behaviour from Alphavantage?

Peter