Member Reservations Disappearing and not showing for approval

Recently we've experienced Member Reservations randomly disappearing within an hour of them being booked. Multiple members have complained of this issue, and I've recreated it with a test account in the Member Portal. This also always coincides with the Reservation not appearing for approval in "New Reservations for Review" even though we have the setting for "A Member Reservation through the Portal must be Approved" turned on for all members.

While testing, I can see the booking on the scheduler from the Admin perspective, but it never appears for approval despite our settings requiring it. When viewing that member's Reservations tab in their account, I can see the reservation with the tag that it is awaiting approval, but the TO DO section does not show the reservation.

Then after some time, the booking will disappear without the admin or member cancelling it. 

Please help, I can provide additional information or testing if needed. Thank you!