Because an annotation feature class is static and separate from the dynamics of a labeling engine, I'm having trouble understanding why my street annotation is altering my labeled features.
More specifically, I have milepost point features that use an expression to essentially place the numbers vertically, like you see in real space when driving down the highway. And it works just fine when the street annotation layer is turned off. But when I turn it back on, some of the labels ignore the expression and revert back to a standard horizontal, left-to-right labeling of the numbers (see related images and note milepost 298 at bottom of map page).
How do I fix this so that the mileposts always (i.e. hard constraint) label according to the expression?