A Singleton in Delphi Tokyo

A Singleton in Delphi Tokyo

I have some code that appears to have stopped working. We have had every version from XE7 right up until Tokyo and I have a singleton in there for doing Debugging to Log files...... For IPR reason I cannot include the source code, but safe to say I used the pattern described in:

http://edn.embarcadero.com/article/22576

However, we made a few mods, so:

var
debugger: TuexDebugLogger = nil;
debuggerRefCount: Integer = 0;

{*****************************************************************************
* Class : TuexDebugLogger
* Function : NewInstance
* Arguments : None
* Action : Overriden NewInstance for singleton
* Returns : An object pointer
*******************************************************************************}
class function TuexDebugLogger.NewInstance: TObject;
begin
if debugger <> nil then
begin
Result := debugger;
end
else
begin
Result := inherited NewInstance;
end;

Inc( debuggerRefCount );
end;

{******************************************************************************
* Class : TuexDebugLogger
* Function : FreeInstance
* Arguments : None
* Action : Overriden FreeInstance for singleton
* Returns : nothing
********************************************************************************}
procedure TuexDebugLogger.FreeInstance;
begin
Dec( debuggerRefCount );

if debuggerRefCount = 0 then
begin
inherited FreeInstance;
end;
end;


This appeared to be working, but now it isn't and we have several distinct instances, instead of 1 !

Has anyone got any ideas as to why it won't work anymore ?
http://edn.embarcadero.com/article/22576