this forum has no access to your return, so we can't see what is happening. is there a passive loss limitation form 8582 which would make some of the interest currently non-deductible. if yo are taking the 199A/QBI deduction it is inflated
From my standpoint allocating some portion of expenses like utilities and real estate taxes to the rental but not mortgage interest would be an imconsistent accounting method that could be challenged by the iRS.
this is what I found on a web search but there is no source for this.
"You must split any expenses – mortgage interest, mortgage insurance premiums, and real estate taxes – between the rented portion of your home and the unrented part. You can also deduct expenses that are normally not deductible, like electricity and qualified home improvement projects."