I am not reproducing this issue on my Sitefinity, 6.2.4910 version, blank project. I attached a simple MVC widget created with Sitefinity thunder,
following the blog post
I sent you and it works fine with both dynamic modules widgets, in master and detail view, and build in widgets(news widget for example).
If you still not resolving this issue I would recommend you to send your MVC widget, so we can investigate it further.
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