LaTeX.org

Here is a workaround using atom editor (https://atom.io/) to open the lyx file as a text file:

Find and Replce with Regex option (.* button to top right of Find button) selected.

Find (regex)

\n\\begin_inset

Replace (note space at the beginning)

\n\\begin_inset

Some replacements change ...

When I import a tex file, the resulting lyx file omits the spaces before insets

e.g. where $c\in\mathbb{R}_{\ge0}^{n}$

becomes

where$c\in\mathbb{R}_{\ge0}^{n}$

in the code pane of lyx, and in the source file

where
\begin_inset Formula $c\in\mathbb{R}_{\ge0}^{n}$
\end_inset

rather than

where ...