Agreed! But how can page selector/Field Card drive the selection of another grid/card which is based on the same filter. For Example I may want to select FY19 and grid should populate FY19 data based on the filter which is applied on the underlying module.
If you are using data as a filter which it sounds like you are then providing the filter is set up on the grid then it should update. Note, as its a data filter you will need to refresh the page to update the filter axis. If you can build this example out in classic then it should also work in the New UX. If this is not the case it could be worth logging a ticket with support so it can be investigated.