Hi, I'm experiencing a similar issue - let me know if I should create a new thread.
I have 2 entries for context menu items in the registry, and the ICON value is specified, in Windows Explorer the icons appear on the context menu, but they don't show up in Opus. I think this has only started happening recently, like in the last month or so.
They were appearing generic in Opus and Explorer. I found an article about the issue and it offered a solution - I downloaded the .reg file for the .ico file type and merged it and it looks like it's fixed.