Google announced that there was a bug which caused review stars to drop out of search results for about a week during the middle of February 2016. Despite the fact this bug only lasted a week, there was enough impact on organic search results which were strongly felt by industry leaders and businesses, with data showing a significant drop in search history for sites that contained review stars.
Initially, it was suspected that Google was going to take out the review stars altogether, with one source from the SEM Post claiming that the use of rich-snippets created a cluttered atmosphere when multiple organic search results had their stars displayed, and thus Google addressed this by creating a more consistent template for search result pages.
However this was not the case, as the bug was announced by Google officially on the 26th of February. Reviews are starting to come back into search results, which can be seen as a positive sign for sites that already have review stars, and they can expect their CTR to go back to its usual rate.