if you filter by one of the available tags on one date, change the date then no gigs will match unless that date also happens to have some gigs with that tag - it just looks like that date doesn't have any gigs and the tag filtering is not visible (but can be seen in the url)
i think the clearest way to communicate this might be to add the counts for how many gigs match the various criteria
so if you've selected "all ages (3)" on 2024-05-26 and then change the date to 2024-05-28 when there are no all ages gigs, then display "all ages (0)" in addition to the counts for tags that are available for that day
if you filter by one of the available tags on one date, change the date then no gigs will match unless that date also happens to have some gigs with that tag - it just looks like that date doesn't have any gigs and the tag filtering is not visible (but can be seen in the url)
i think the clearest way to communicate this might be to add the counts for how many gigs match the various criteria
so if you've selected "all ages (3)" on 2024-05-26 and then change the date to 2024-05-28 when there are no all ages gigs, then display "all ages (0)" in addition to the counts for tags that are available for that day