I dunno how much any of y'all have interacted with the US federal government, but they love using acronyms for very specific things that probably don't need acronyms.
One of them is "unanticipated problem (UP)", which comes up in human subjects research. The term UP is first mentioned in Dept of Health and Human Services (HHS) regulations at 45 CFR 46, and is defined by the Office of Human Research Protections (OHRP) as follows: