GREP to apply subscript to uppercase single character followed by a single digit

[Inélsòre]

I'm sure to have already asked this but I cannot find it anywhere, nor on search engines. 

In a music-related text, I need to show the octave of a note with a subscript digit. 

So, the middle-C on the piano would be C3 with 3 being subscripted. 

I am trying this GREP but it's not working:

(?<=[A-G])\d

This should be positive lookbehind for uppercase letters A to G, then applying the character style to the single digit following it. 

Any idea why this may not be working? 

Thank you!

[jmlevy · Accepted solution]

It works perfectly for me. Are you sure that the character style you apply via the GREP syntax is properly set? 

[Inélsòre]

Here is the Character Style  (there is nothing else needed but Subscript):

And here is the Paragraph Style's GREP page:

 

And here is the result I get (that is, nothing): 

[Inélsòre]

If you want to check with a sample document, I have pasted some of the offending text in the attached InDesign file below.

Thanks!

[jmlevy · Accepted solution]

I don't know what happened, but I just re-typed the full string of your GREP style it it works now. 

[Inélsòre]

Woah! That worked for me too! 

Unbelievable but, as a Jedi Master would say, "that's why you failed"! 😂

Thank you!