We had an interesting bug recently. One of our books was published by Amazon KDP, but it appeared as ‘unavailable’ immediately after publishing.
This is very strange. Amazon prints books like ours on demand when they are ordered: they can never be out of stock (or even ‘in stock’ for that matter: stock is meaningless).
Another factor was that we could order the book in any other country – it was available from the US version of Amazon, the French version, and the Brazilian version.
After a week (which felt like a very long time) the book became available again and was ordered as normal.
Our working hypothesis is this: Amazon has a limited number of print-on-demand machines in the UK. We know some of them are in Luton (they give the test copies to a local infants school here). For some reason a proportion of the machines stopped working for a week and Amazon stopped offering some of their print-on-demand catalogue while the machines caught up.
Interestingly – We suspect part of the problem was Amazon’s Prime system – because they guarantee delivery within a short timeframe, they weren’t able to offer the books at all.
This is all guesswork of course, and we post it only because it’s relatively informed guesswork. We’ve published over 250 books on the platform and ordered over 10,000 copies, so we have some experience of the system.