I've looked at many similar questions on TeX overflow to no avail. I've tried using both the polyglossia and the babel packages but neither had any effect. I'm assuming the issue lies a little deeper.
Here is a MWE:
\documentclass[10pt,a4paper]{article}
\usepackage{graphicx}
\usepackage{fontspec}
\usepackage{polyglossia}
\setmainfont{LMR12R-Gregory}
\setdefaultlanguage[variant=american]{english}
\setotherlanguage{russian}
\begin{document}
\textrussian{Привет!}
\end{document}
Below is shown the text on the PDF generated by this code:
What causes this? The font has both latin and cyrillic characters. In WordPad it works correctly, so I'm not sure what's going on. Any help would be highly appreciated.
As per the comments below, here is a dropbox link to the font: https://www.dropbox.com/s/4grjkah8x6ldgul/LMR12R-Gregory.ttf?dl=0
Here is a pastebin of the log. There were no issues or errors shown in TeXStudio. https://pastebin.com/jCx7w7s1
\tracinglostchars=2
and/or look in the log file for warnings about the font not containing the requested characters?