XeLaTeX doesn't find lmroman font, despite installing lmodern fonts

Hi I’m a newbie to the latex world and I have tried as hard as I could, to find the answer in the forum, yet I haven’t been successful.

I have installed texlive on ubuntu 18.04 via the command bellow.

apt-get install texlive-full

but while running template latex codes with xelate (in TexStudio) I get this error:

Font TU/lmr/m/n/10=[lmroman10-regular]:mapping=tex-text at 10.0pt not
loadab le: Metric (TFM) file not found normalsize

and yes I have installed lroman fonts via both

apt-get install fonts-lmodern

and

sudo apt-get install lmodern

your help will be greatly appreciated.
Thank you.