Can't change diameter symbol font in dimension

I have a monospace dimension style which uses the Courier New font. Recently, I've noticed that the diameter symbol is bolder than the text. The reason is that the symbol is in Arial while the dimension itself is in Courier New. If I explode the dimension and try to change the symbol font, it won't change it to Courier. Instead, it changes to Country Blueprint which is the font listed just above Courier. I tried entering the symbol in MTEXT and the same thing occurs. If I enter the symbol in MTEXT using ALT+0248 I can change it to Courier but entering from the symbols menu, I can't change the symbol to Courier although I can change it to almost any other font. I tried updating the font but that had no effect.

Any help will be greatly appreciated.