GIS Module Favourites Outdated

I am creating a series of example maps on a local server and just created 4 maps which I saved to my favourites. Unfortunately all, but one of the maps gives the following error "Favourite is outdated - please create a new one". Tried logging in and out etc, but seems like I have lost my maps. Any idea what this error message means / how I can avoid it?

OS = Linux, Browser = Chrome....