LyX ⇒ Tex variables not expanded in 'export to plain text'

[vermaudh]

I am using lyx 2.1.4
If I add any tex macros ( using Menu-> Insert-> TexCode ), they are not expanded while exporting to plaintext.
There is just whitespace where the expanded macro value is expected.
If I export to PDF (pdflatex) it works fine.

I also tested this with lyx/2.2.4, same issues.
2 questions :
1. Is this a known issue/ if so do we have a fix version ?
2. If anyone knows a possible workaround that I can try?

Any help is much appreciated, thanks.