I'm implementing a datetime selector for events taking place mostly in the evening. The audience is mostly based in the US, but there might be international users as well, so I followed this suggestion of providing a 24-hour time picker (like this one from Material UI) for clarity.
However, some casual testing has revealed that US-based friends would choose 6AM when they meant 6PM. The sample size is small, but one pointed out that the hours after 12 are also smaller and inside the other circling, suggesting they'd be secondary, more like minutes to select after selecting the hour. In reality, hours should have equal emphasis from 0 to 23, and actually evening times should be emphasized since these events would take place in the evening.
What would be a clearer way to provide a time selector? AM/PM indicators instead? I'm afraid those may not be as common in some locales, while the 24-hour clock is universally understood, even if less used in the US.