It sounds to me like the BizTalk 2010 WF interceptor was just not rewritten to handle the changes to the WF functionality in .NET 4. I have not looked at the implementation for the interceptor but it is probably based off of workflow tracking which must
have changed in .NET 4.
To make it work you would need to build a custom activity in your WF 4 workflow that would write to the BAM view. You might try using SQL profiler to determine which objects are called/saved by the interceptor for a .NET 3.5 workflow and then reproduce this
in your .NET 4 workflow.
Another approach would be to expose a workflow service on .NET 3.5 to interact with the interceptor and then have the .NET 4 workflow call into it for tracking purposes.
I am not sure if you could use the Interop activity in WF 4 and then host a .NET 3.5 activity there that the BAM interceptor listens to but it would be worth a try.
Thanks,
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