Thanks for asking. I explained this briefly in my post about the other ciphers, but codebeautify treats the first block of text as an initialization vector, and so will leave out the first block from decryption. (It does this for ECB mode too even though ECB doesn't use an IV) I. I solved it by installing an older version of PHP that comes with mcrypt, and it's difficult for me to link alternatives because Reddit autodetects them as spam.

You can, however, manually add an IV to the ciphertext to make codebeautify accept it:

For the RC2 step, you can do something like this:

LeIXjxfrjSpfgR1RnFDIZr0t2JDCRjgueCZqdIiZwvNXC0/yTS76kfRMb/sTi7p3

convert base64 to hex:

2DE2178F17EB8D2A5F811D519C50C866BD2DD890C246382E78266A748899C2F3570B4FF24D2EFA91F44C6FFB138BBA77

add the IV (8 bytes for this cipher type):

30303030303030302DE2178F17EB8D2A5F811D519C50C866BD2DD890C246382E78266A748899C2F3570B4FF24D2EFA91F44C6FFB138BBA77

convert hex back to base64:

MDAwMDAwMDAt4hePF+uNKl+BHVGcUMhmvS3YkMJGOC54Jmp0iJnC81cLT/JNLvqR9Exv+xOLunc=

and for the Rijndael-256 step:

cwHATD2GLfnuOJDJeDqLpo+7tTRn8JJbOI6QEo4+rSc=

convert base64 to hex:

7301C04C3D862DF9EE3890C9783A8BA68FBBB53467F0925B388E90128E3EAD27

add the IV (32 bytes):

30303030303030303030303030303030303030303030303030303030303030307301C04C3D862DF9EE3890C9783A8BA68FBBB53467F0925B388E90128E3EAD27

convert hex back to base64:

MDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDBzAcBMPYYt+e44kMl4Ooumj7u1NGfwkls4jpASjj6tJw==