Scheduled Summary notifications in iOS often won't open

The notifications are set to display as stacks. The scheduled summary stack appears normally, but it can't be separated into individual notifications. The only actions possible are to dismiss the entire group or wait for it to disappear. This has been happening on my iPhone SE 2020 ever since scheduled summaries were introduced with iOS 15 and I feel it happens to about 70% of the summaries. Is this fixable, or simply a bug that needs to be reported to Apple?