[CONNECT C# addin] app does not release excel COM objects

I have an addin that connects to excel and writes things to the excel file.

I am running into a problem where the addin is not releasing the excel COM objects. I know I am releasing everything correctly in my code. the only way I have been able to get the objects released is by closing microstation.

I put the same code into a stand alone app for connecting to an excel COM object and releasing it via code and it is released (so that verified I am releasing it). So does anyone know why MicroStation is holding onto this?

Any one ever ran into this or have any ideas to try.

this posts describes how to release COM objects, but again a stand alone app has no problem releasing the COM objects.

https://stackoverflow.com/questions/25134024/clean-up-excel-interop-objects-with-idisposable/25135685#25135685