Inline matrix display

[MqCreaple]

I tried to write an inline matrix like this:

Some text blah blah $\begin{bmatrix} a & b \\ c & d \end{bmatrix}$

However, the matrix was rendered to this:

[a   amp; b c  amp; d]

But the same code worked well for a block equation:

$$\begin{bmatrix} a & b \\ c & d \end{bmatrix}$$

Do anyone got any solutions?