Metrotube has picked up an update, which is readily available on the Windows Phone Store. The latest release is only a minor bump for the app, but does address multiple issues fans of the unofficial YouTube client may be experiencing.
Version 4.6.2 fixes an issue that could prevent you from logging in, as well as addressing problems found on search pages in various languages. The changelog lists "other minor fixes", so we can assume the developer has worked tirelessly to squash all those annoyances that prevent you from enjoying a bug-free experience.
Thanks, Mark W., for the tip!