Can't delete bookmarks

Hi, I can't delete any bookmark. I have tried it : on the page, by clicking the star and "remove bookmark" ; in the bookmark list, by right-click and "delete bookmark" ; in the bookmark list, by using the "organise" tab and choosing "delete bookmark". It affects, as far as I can tell, all my bookmarks. I can add new bookmarks, but not delete them. I clean my cache regularly, and my browser is up to date. I use Windows10, in case that is relevant. I would be grateful for any help you could provide, Have a good day, J.