Please use \mathbf instead of \bm. So for example write:

$\mathbf{O(\log n)} + \mathbf{O(\lambda,\,\epsilon)}$

Alternatively, if you really want to use \bm, you need to include the following package in your header.tex (click Edit Macros in Document Settings)

\usepackage{bm}

Updated on: 01 / 20 / 2020