Text that works correctly in a text object directly is not working correctly when input into a Document User text value and then referenced in a text object.
Example:
My direct text input:
100[[1/2]]" W x 2 [[3/4]]" D x 30" H
In this instance there is one, but it takes a while to stumble on it because multiple factors need to come together.
Store the three dimensions as separate document user text entries, omitting the " symbol, and in the text block precede the first reference with some plain text.