I've investigated your installation and according to logs you've made multiple changes to the plan with the users subscription being activate at the time of change. I believe these changes have resulted in the mis-matched dates. I do not have database access, but would seam the users subscription dates are off and do not any longer match those of the plan.
The users subscription are marked and considered Active, but due to the Expire date being that of 2009 the plan does not appear as it is expired, but it's Expired with the status of Active; which results in its disappearance. Confusing I know, but short response is try to avoid major changes such as price, duration, grace period, etc.. when a plan has active subscribers or it can cause mis-matches such as this.
I've set the users subscription as Expired accordingly, but this does not fix the damage done to the database. The subscription is likely missing it's parent_plan ID. I don't know without database access. I can try fixing this (be sure to do a database backup) if provided database access or you can delete the subscription your self manually from your database (or alternatively try and fix it).