If I open a private window and then right click on any link and choose the "Open Link in New Tab" context menu option, a new tab will appear for a few milliseconds before immediately closing and the link will never load. The new tab closed in this manner will not show up in the history of closed tabs either (likely because this list is only updated after a tab fully loads a page before being closed, which obviously never happens). I have not added any new addons since long before this problem started, but I did try disabling any tab related addons to no effect.