After trying several options the fix I needed was an uninstall/reinstall of AutoVue DD 20.2.2
No idea what caused it to stop working though.
Happened again, after running a different application using an older version of the AutoVue ActiveX.
OCX registration does not allow more than one version, ocx is a product tied to a single clsid
the latest registration will remove any previous link
It is simply not a use case (any) OCX supports
Just an addition: the problem appears to be caused by opening/closing AutoVue instances one after the other. Making an AutoVue wrapper that is a singleton prevents the issue from occurring (so far).