If you are viewing the features board by Release columns, ungrouped, the default releases will be all releases in the workspace you're on. If you add multiple workspaces to your board filter, this column filter does not adapt so you do not see any releases for the additional workspaces. If you try to filter, you see all possible releases in all workspaces you have access to so there is no easy way to show all active releases for the workspaces you've selected for the board
Hard to filter on the releases you want based on workspace selection
Make the column selection adapt to multiple workspaces (ie. show all for workspaces selected, etc)