Complex molecules can have several stable crystal forms, and it can be that one is useful while another is not. And yet your lab, and other labs, can be taken over by a preference for crystallising into an undesirable form.
… the original form of ritonavir was recovered and brought back into production after a great deal of effort, although not before HIV-positive patients had seen their medicine disappear from the shelves for months (and not before Abbott had lost a quarter of a billion dollars along the way)
https://blogs.sciencemag.org/pipeline/archives/2019/11/26/perverse-polymorphism
“This is why all of us at Abbott have been working extremely hard throughout the summer [of 1998], often around the clock, and sometimes never going home at night. We have been here seven days a week and we will continue to do so. We have cancelled vacations and asked our families for their understanding and support. This is not an issue that we take lightly.”
“There were several sub-teams of three to 600 people per team working full time in different areas. We also called on as many resources as we could.”
“We tried everything. We conducted countless experiments. We reconditioned our facilities. We rebuilt facilities and new lines. We looked at alternative sites. We visited a number of [other] organizations around the world…to see if we could start clean in a new environment free of Form II.”
“In a matter of weeks—maybe five or six weeks, every place the product was became contaminated with Form II crystals."
via Slate Star Codex