Why do I get empty graph when adding 'Abs' function?

Might it be the way Mathematica deals with the derivative of Abs[]? For example,

D[Abs[5 - 2 x], x]

returns

-2*Derivative[1][Abs][5 - 2*x]

Try

Plot[Evaluate[D[Sqrt[(5 - 2 x)^2], x]], {x, -10, 10}]

I'm also wondering why Mathematica doesn't treat the derivative of Abs as normal way. But here is a solution.

Plot[Evaluate@ComplexExpand[D[Abs[5 - 2 x], x]], {x, -10, 10}]

As of V11.1, another available approach is to use RealAbs instead of Abs:

Plot[Evaluate[D[RealAbs[5 - 2 x], x]], {x, -10, 10}]

Note that Abs, as a function of a complex variable, is not differentiable, which I mentioned in a comment earlier.