All my reissues were held up at Amazon for several weeks while authorship/ownership (reversion of rights) /copyright holder/ebook rights holder were verified by Amazon via my new ebook publisher, not made any easier by the fact my author name had changed from Scott Wilson to Chris Scott Wilson (so all my books came under the same author name) ! However irritating it was at the time, at least they were checking. For my next reissue,
Scarborough Fair I expect further delays as the publisher who originally produced the paperback/audiobook went bankrupt, so there are no actual documents confirming reversion of rights. However, I have been advised that if a company goes bankrupt, any contract between you and them is void, as a company that no longer exists cannot hold any contract with you.
http://www.chrisscottwilson.co.uk