That might be so, but they only ceased as a customer late last...

That might be so, but they only ceased as a customer late last year. refer ASX 24/10. So, how much of the Dec17 Receivables balance was due to AFD? If any, at all, then that may well be at risk of being written off.

Conversely, the question arises as to whether any preferential payments were made. Whenever an administration situation arises (and this one looks almost certainly like going straight on through to liquidation), then the question of clawback /preference payments etc will all undoubtedly be looked at even if they don't ultimately find any traction.

Then there is the closure of ADF as a brand outlet in reference to CDC's branded products, including here again, how much might very well be currently owed by ADF. Again, refer to the following from ASX 24/10:
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"The AHF Board submitted pricing based on competitive but realistic margins and declined to offer lower contract packing prices for the lower volumes being sought and as a result the supply of service for packing Aussie Farmers branded milks to Aussie Farmers will cease. The sales of yoghurt will continue.

The Board appreciates that Aussie Farmers have now also commenced ranging Camperdown Dairy branded Jersey and Free Range milk and are interested in other Camperdown Dairy branded products being ranged."

Given the ASX announcement of 24/10, there is some doubt as to whether the ADF selling (!) had ceased altogether by 24/10, (2) would cease effective 24/10, or (3) was scheduled to now cease but may not have ceased until, for example, 31/12.

So, perhaps you are right but very likely AHF will have been caught up in all this with (*) loss of branded, premium or alt milk ie: yoghurt outlets to market, and (*) some measure of receivables loss as a likely crediotr of AFD.