co-owned property occupied by one owner

Hi, my ex and I own an apartment with 50/50 ownership and also have a mortgage under both names.  We decided to keep the way it was when we divorced.  He stays and lives in the apartment and pays all the mortgage and he will claim the mortgage interest and property tax on the tax return.

Is there any problem that I need to concern about? Is 50% of his monthly mortgage payment considered rental income to me?