Hi there @bmillerlab - looks like the tool we use for building the docs (Sphinx) broke their search functionality in the version used to build the 2019.4 docs. Hopefully in the 2019.7 release of QIIME 2 we will be able to use a newer version of Sphinx that has the bug fixed. In the meantime, you can use a search engine like Google to perform site-limited search: site:docs.qiime2.org/2019.4 demux
Thanks! :qiime2: