What I was asking is if I can claim the mortgage principle as a loss
No. The principle is never deductible. Only the interest is claimed as you have always claimed it.
I'm not listing anything in the asset/depreciation
I think we're having a communications disconnect here. You must have at least the property itself listed in the assets/depreciation section, since I'm sure you're aware you're required to depreciate the property for so long as it's in service. If you took the property out of service in 2021, then you can't just delete the asset. You "must" show it's disposition. Also, if you removed the property from service, that severely limits what you can deduct, to just property taxes and mortgage interest as a SCH A itemized deduction. So I'm confident (and hopeful) you've left the property in-service, and have continued to depreciate it in the assets/depreciation section.
