Entertainment attorney based in Nashville here. I deal with producer-artist royalty disputes regularly and this is one of the most common issues in the music industry. The answer almost always comes down to what the producer agreement says about ownership splits and what type of royalties we are talking about.
There are several distinct revenue streams in music: mechanical royalties from sales and streaming, performance royalties from radio and live venues, sync licensing fees from TV and film placements, and master recording royalties. A producer claiming all royalties is almost certainly overreaching unless they also wrote 100 percent of the composition, which is rare. Even in work-for-hire arrangements, the scope of the producer claim is usually limited to master recording royalties or a percentage thereof.
If you have a signed producer agreement, check whether it specifies the producer royalty as points on the master (typically 3-5 points for independent producers) versus a percentage of publishing. These are very different things. If the agreement is ambiguous or silent on specific royalty types, courts generally construe ambiguity against the drafter.
At 141K in dispute, you need a music industry attorney, not a general practitioner. Many entertainment lawyers will take an initial call for free and some work on contingency for royalty disputes. The Volunteer Lawyers for the Arts in your state is another good resource if cost is a barrier. Do not wait on this - the longer royalties flow to the wrong party, the harder it becomes to recover them.