
Reset this character style to Base style
Then reapply additional format requirements
I exported the file to IDML and changed the name to .zip - then extracted the content
There's a style XML file
And in here
ExtendedKeyboardShortcut="0 73 1"
This is a numerical representation of a keyboard shortcut. In Adobe's system:
0 = no modifier (or sometimes platform-specific)
73 = ASCII code for the uppercase letter I
1 = usually indicates the Cmd key on macOS or Ctrl on Windows
Seems the shortcut got broken or something or someone before you was using a Custom Shortcut or a plugin/script or some other third party tool to make shortcuts and assigned 'i' or 'I' to make the shortcut in the Style settings so they could apply the style quickly.
Typically you cannot assign random letters to keyboard shortcuts for styles.
You can see an ExtendedKeyboardShortcut reference in the text of the code below
</CharacterStyle>
<CharacterStyle Self="CharacterStyle/Reference italic" Imported="false" SplitDocument="false" EmitCss="false" StyleUniqueId="970362db-891e-4bdf-867b-6deb6e9e2fc5" IncludeClass="false" ExtendedKeyboardShortcut="0 73 1" KeyboardShortcut="0 0" Name="Reference italic" FontStyle="Italic" Ligatures="true" NoBreak="false" Underline="false" StrikeThru="false">
<Properties>
<BasedOn type="string">$ID/[No character style]</BasedOn>
<PreviewColor type="enumeration">Nothing</PreviewColor>
<AppliedFont type="string">Proxima Nova</AppliedFont>
</Properties>
</CharacterStyle>
Either way - the Keyboard Shortcut assigned in the style was mapped to it in the file - but not visible in the Style.
Minor corruption.
Reset your style to base and it seems to correct it.
Alternatively instead of resetting to base
Assign the Custom Short cut in the style itself Option I works and not assigned to anything else.
Then it behaves normally.