There are still some Windows shell extensions that prevent One Commander from opening the file/folder context menu. If you have this issue please try running this utility:
(scroll to "Download ShellExView for x64" near bottom of the page)
then check
Options>Hide All Microsoft Extensions,
sort by type to see all "Context Menu" in Type column,
then disable one by one and each time check if OC can open context menu.
Once you find which causes the error, please report to