Even more detail: The property with the $300k mortgage was converted to a rental property in April 2019, so I have prorated and split the mortgage interest (and property tax) amount between the sections that add it to Schedule A and Schedule E; not sure if this is somehow breaking TurboTax.
The answer is in your other post, however I will add the link to the worksheet here for your convenience. Review the worksheet to average your loan and determine the percentage of allowed deduction, then manually enter the correct amount of mortgage interest. Keep the worksheet for your files.
- IRS Publication 936 (page 12)