Beamer Metropolis Theme clashes with tikz, removes content from tikzpicture

The theme loads a pgfplotsthemetol.sty which sets various pgfplots related things. Beside other it resets the compability level. You could reset it again:

documentclass[xcolor=dvipsnames,aspectratio=149,10pt]{beamer}

usepackage{pgf,tikz,pgfplots,tikz-cd}

usepackage{mathrsfs}
usetikzlibrary{arrows,intersections, pgfplots.fillbetween}

usetheme{metropolis}
AtEndPreamble{pgfplotsset{compat=1.15}}
begin{document}
begin{frame}
abc
 begin{tikzpicture}[line cap=round,line join=round,>=triangle 45,x=5.0cm,y=5.0cm,scale=0.45]
begin{axis}[
x=5.0cm,y=5.0cm,
xmin=-1.0,
xmax=1.0,
ymin=-1.0,
ymax=1.0,
xtick={-0.5,0.0,0.5},
ytick={-0.5,0.0,0.5},
xticklabels={,,},
yticklabels={,,},
line width= 2pt
]
clip(-1.,-1.) rectangle (1.,1.);
draw [line width=1.25pt] (-1,1.)-- (1,-1.);
draw [->,>=stealth,line width=1.pt,dash pattern=on 2pt off 2pt] (-0.4,0.4-0.25)-- (-0.4,0.4+0.25);
draw [->,>=stealth,line width=1.pt,dash pattern=on 2pt off 2pt] (-0.4-0.25,0.4)-- (-0.4+0.25,0.4);
draw [->,>=stealth,line width=1.pt,dash pattern=on 2pt off 2pt] (0.4,-0.4+0.25) -- (0.4,-0.4-0.25);
draw [->,>=stealth,line width=1.pt,dash pattern=on 2pt off 2pt] (0.4+0.25,-0.4) -- (0.4-0.25,-0.4);
end{axis}
end{tikzpicture}
end{frame}

end{document}

With a current LaTeX you could also forbid metropolis to load this style, and to leave your settings alone.