Problem with handle class destruction when objects reference each other in field of struct

The below example may be more complicated than necessary, but is the simplest thing I could find that replicates the behavior I'm seeing. I have three classes:

classdef MyClassA < handle

    properties
        x
        y
    end

      methods
        function this = MyClassA()
            this.x = MyClassD( 'a' );
            this.y = MyClassD( 'b' );
        end
    end

end

classdef MyClassB < handle

      properties
          myStruct
      end

      methods
          function setMyStruct(this, value)
              this.myStruct =  [this.myStruct, value];
          end
      end

end

classdef MyClassD < handle

      properties
          data
          reference1
          reference2
      end

      methods
          function this = MyClassD( value )
              this.data = value;
          end
      end

end

Script:

mcb = MyClassB;
mca = MyClassA;
% mca.x.reference1 = mcb;
mca.y.reference1 = mcb;
mca.x.reference2 = mca.y;
mca.y.reference2 = mca.x;
s.f1 = mca.x;
mcb.setMyStruct( s )
s2.f1 = mca.y;
mcb.setMyStruct( s2 )

clear classes

When I run the above script I get a warning "Warning: Objects of 'MyClassD' class exist. Cannot clear this class or any of its super-classes." However I don't get this warning if I remove any of the following from the script:

1) mca.y.reference1 = mcb;

2) mca.x.reference2 = mca.y; mca.y.reference2 = mca.x;

3) s2.f1 = mca.y; mcb.setMyStruct( s2 )

This behavior seems very odd to me. Even stranger, I don't get any warning message if I put an empty delete method (destructor) in either MyClassB or MyClassD (in the form below).

function delete(this)       
end

I'm using Matlab 2012a WinXP. Can others replicate this behavior and better yet explain it.

[Daniel Shub]

I cannot replicate this on R2011a Linux.

[Chris]

Nor can I in R2012b on WinXP. Though nor can I find a bug in the Matlab bug report that was fixed in 2012b relating to this either...

[Sean de Wolski]

Is it reproducible if you restart 12a?

[Chris]

Yes, can reproduce it without fail in R2012a. I've restarted Matlab and my PC and am able to reproduce it in all cases in R2012a.

[Chris]

Also get the same error in R2012a on Mac OS X

[per isakson]

Your problem resembles

    Why am I unable to clear class definitions if one of the classes
    contains a property initialized to a class having an anonymous 
    function as its property in MATLAB 7.11 (R2010b)?

    Date Last Modified:  Friday, October 22, 2010
    Solution ID:    1-DIYLPG
    Product:        MATLAB
    Reported in Release: R2010b

There are a few old bugs related to "Cannot clear this class or any of its super-classes". They are reported as fixed. However, I'm convinced there are more to be reported.

[Chris]

Yes this seems to be one that went unreported and quietly fixed in R2012b.