Heres your explanation for lack of depth:
APO is trading ex-divdend today meaning all outstanding orders as of close yesterday have been 'purged'.
As per Commsec: A stock has turned ex-entitlement
All orders in market depth will be purged on market close the day prior to a stock turning ex-entitlement (eg ex-dividend, ex rights, ex capital return etc.). If you still wish to go ahead with your order please replace it in the market.
APO Price at posting:
$5.67 Sentiment: Buy Disclosure: Held