I tried a few examples using varbinary(8000) in an attribute, but I am unable to reproduce the bug. Can you reproduce the bug consistently, using a small model that you can paste here (XML). Perhaps a single anchor and attribute?
I've tried a few times to create a simple model and cannot reproduce the bug either.
I am very reluctant to believe in non-deterministic behaviour from software unless all other explanations have been eliminated. That being the case I must conclude that there was some repeated error on my part when I found and examined the 'bug'.
If I ever encounter this again I will try to provide the model of course, but the original has been substantially modified;
Please accept my profound apologies for wasting your time and that of anyone else who has read this thread.