I've spent two days messing about with this now!
If I install TexLive from the repositories, I'm unable to use tlmgr to update it, and Lyx can't find any of the document classes.
the "Tex Information" config option lists them all happily, and LaTex works fine, so there's obviously something broken in Lyx (and yes, I've reconfigured, texhashed and even rebooted)
SO, uninstalling TexLive and reinstalling from the TexLive installer (not the apt repos) works fine (except the default install location is /usr/local which requires root permissions despite installer instructions to not install as root. I had to manually create the install directory and chmod it to get the install to work as myself). I have a working, tested Tex install!
but now, of course, I can't install Lyx because apt doesn't know that I have a working Tex install and insists that I need the tex-common package installed with my lyx package, which will overwrite my lovely working tlmgr-able tex install with an old version that won't work with tlmgr and put me back with Lyx not being able to find document classes.
Is it always this hard? The just all feels broken to me...What am I getting wrong? How does anyone get Lyx working?