Currently, when a membership is manually given an end date (e.g., May 20), the system does not allow check-ins on that day. This is because our background process, which handles cancellations, deactivates memberships at the start of the end date, rather than at the end of the day.
Workaround:
Some users set the end date to one day later (e.g., May 21) to allow access through the intended final day.