State Farm confirmed liability denial = coverage denial, but Farmers won’t apply my UM/UIM. What now?

I was hit by another driver. Their insurer (State Farm) denied liability. I called today for clarification, and the representative told me that “declines liability is the exact same as denies coverage,” and that they are not providing any coverage for my property damage. She also said the only reason the wording in their system can't be updated to say “denies coverage” is because she doesn’t have access to change the phrasing and it's automatic.

My insurer (Farmers) documented the liability denial but is still saying it doesn’t count as a coverage denial, so they won’t apply my UM/UIM property damage coverage.

Has anyone seen this before? Does a liability denial trigger UM/UIM? What’s the best next step?