Hello Firefoss, if you do not see the "Go parent folder" on right click, that can only mean that you are not using the BSP2 add-on sidebar = you are probably on the native FF bookmark sidebar. You need to switch to the BSP2 one.

You should see at top right a yellow star with a +, inside in the toolbar -> click on it to see BSP2 sidebar appears / disappear

When you are on the BSP2 sidebar (not on the FF native sidebar), If you still do not see the "Go parent folder" action on right click, please open an issue on https://github.com/aaFn/Bookmark-search-plus-2/issues so that we investigate (which FF version do you have, which OS, a screenshot of the BSP2 sidebar if possible with the right click menu open .. etc ..).

Let me know, aaFn.