Q. Bisantrene is not new. How can RAC monetise if it is out of patent?, page-27

My memory was that because of the crystallization issues, it was dropped in pursuit of another drug they had that was showing promise. Then during mergers and acquisitions Bisantrene, which had crystallisation issues and failed attempts at solving it, was 'lost' to put it colloquially

I don't think 'lost' and 'crystallisation issues' are entirely separate things, it's just part of the history of the drug up until modern times, where reformulation and expanded understanding of MoA have generated a renewed interest.