Hi - If I understand correctly, you just want to report on the original expiration date? I believe Sharon Horton has filed this ER 1-BBY0MN on your behalf to track the issue. The workaround available to you are: Create a custom reportable field then assign it an expression to pull value from the existing Original Expiration Date field. You can initially make it visible in the Details section so that you could see if its working and then later on remove it since it will only be used for report.
There are a couple of downsides: 1) Existing contracts have to be remediated manually 2) this uses up a customer field for data that already exists in the system