Button state formatting issues when changing text

Hi everyone,

I'm having an issue at the moment with my button state text formatting. I have a button with standard, hover, down and selected states. The text remains the same formatting for the standard, hover and down states, and is a different colour and weight in the selected states. The issue arises when i change the text in my standard state whereby when I do, the selected state loses all formatting (please see attached video). This problem occurs when using the built-in selected or visited states and custom states, but doesn't occur on any of the other states.

I've tested various permutations or sizes and fonts and when the same font and same size is used, the text isn't reformatted. However, when there are different fonts and/or different sizes in the same text box, the reformatting issue occurs.

I've tried various workaround with having separate text boxes in the states and not having the text in the button itself, but this results in me having to update the text in each state instead of just one, but also the way i have to do it to compensate has some adverse affects on interacting with the button (namely, once selected, the workaround doesn't allow for the other states - hover and down, to be activated) so isn't a viable option. 

Has anyone ever experienced this before or have any thoughts on potential causes/workarounds? Any help would be greatly appreciated.

Many thanks,

Andy