Can't scroll through this LaTeX expression

[MDH]

This is my LaTeX expression:

$$
\begin{cases}
P(x,y) \\
z=x+j\ y
\tag*{helloworld helloworld helloworld}
\end{cases}
$$

Just can’t scroll to see the rest like I would usually be able to do with other equations, anyone know what’s going on? (Only tested on MacOS for now, see if you can reproduce it )

Thanks in advance!

[MDH]

Only happens with \cases{}, as this works:

$$
\begin{align}
  a &= b \\
  c &= d \tag*{this is the equation I wanna comment}
\end{align}
$$

[WhiteNoise]

I am not sure I understand but I can’t reproduce this problem.

[MDH]

Does this:

[MDH]

Basically the a=b, c=d etc. get moved a lot further right than they should be, and what makes matters worse I cannot scroll the block internally to move to their position and see the whole formula