I was having the same issues and noticed that I had my text and other layers nested in groups, probably from detaching from old symbols and creating new ones. Once I removed all the nested groups, the text resized.
You can not increase an image's PPI while maintaining it's width and height and maintain quality at the same time.
To determine the physical size of an image at print resolution, divide the image's current pixel width and pixel height by the output DPI.
Pixel width / Print DPI = print width
Pixel height / Print DPI = print height
So, for a 2448x3264px ...