Had a look at the T&Cs, says nothing about Opal being an exclusion (unless it is a "gift card")?
15.4 Eligible Shop means any transaction at a Participating Woolworths Group business in which you spend at least $10.00 excluding any Excluded Purchases.
15.5 Excluded Purchases means the excluded purchases specified in clause 4.2.1.7 of these Terms and Conditions.
4.2.1.7 Eligible Shop excludes the following purchases in respect of the various Participating Woolworths Group businesses as follows:
1. Woolworths supermarkets in store and online: Smoking/Tobacco products and accessories, Gift Cards, Cash Outs, Home Delivery Charges and Internet Cafes;
2. BWS stores: Smoking/Tobacco products and accessories, Cash Outs and Gift Cards.
Although it does say it may take 72 hours for any WW dollars to show up on your account.
I definitely did not buy any excluded items. All food.
That's best that I can find. Interested in where you saw that Opal top-ups are excluded?