I now have a small tool (
here) prepared that all extensions that are not "compatible" as we are known lists.
"Compatible" sounds a bit stupid, because in each context menu extension should be compatible with other. But I remember roughly (must be 5-10 years ago), that, when it comes to Explorer extensions, some extensions are incorrectly restrained able to influence others (whose error handling has not been expected).
If all concerned had about the same mean another extension (the tool includes known system enhancements that runs on our test system, already out), which could lead to it that we can reproduce the error.
So please test and post the Unknown section here