Why are my formulas jumping up and down on the textline?

Why are my formulas jumping up and down on the textline?

This is one of the major issues with the current version of Math.

What 'current version'?

What happens is, that your formulas always are inserted vertically centered with respect to the textline. If the formula is not symmetrical vertically the baselines of the text and the formula will not be aligned.

You can correct this by dragging the formula up or down using the mouse.