UV SSI has been monitored from space since 1978. This is accompanied by the development of models aimed at reconstructing UV SSI variability by relating it to solar magnetism. There is controversy between the various measurements and models in terms of the wavelength-dependence of the variation over the solar cycle. This sees the application of the various data sets to climate models yield qualitatively different results. Here, we highlight the main discrepancies between available records and reconstructions. More importantly, we discuss the likely causes.