Why am I having to enter rental property building depreciation although TurboTax has had the same data for the past five years?

The depreciation should calculate automatically based on your entries in previous years. You should work through your rental entries until you find a page that summarizes your rental income and expenses. You will see an option for Assets and when you work through that section you should see an entry for the building. If you don't, then it may have gotten deleted, in which case you can re-enter the cost and date put into service, then TurboTax will calculate the previous and current year depreciation automatically.

There have been a lot of questions about this over the last few days.  I suspect there is a 'bug' that is causing problems with the depreciation not working right.

I am having the same exact issue. I'm pretty convinced it's a glitch and I hope they fix it soon 🙂 Here's my thread about it:

https://ttlc.intuit.com/community/investments-and-rental-properties/discussion/my-residential-rental-real-estate-asset-is-not-showing-up-in-the-list-of-assets-that-i-depreciated/00/1805632