Snyk uses the configuration of your project to build a definitive dependency tree. For the Maven project, if the project is configured to use Maven Wrapper, Snyk will follow the same. If Maven Wrapper is not correctly installed, the user would see an error similar to Error: Could not find or load main class org.apache.maven.wrapper.MavenWrapperMain
As suggested in the problem statement, this is usually related to the Maven Wrapper setup. To resolve this you either need to install Maven Wrapper for the project correctly or otherwise remove the Maven Wrapper config from the project completely including the mvnw in the root of the project.
Removing the Maven wrapper completely from the project should force Snyk CLI to use the globally installed Maven and thus resolve the issue. This will allow Snyk CLI to build the dependency tree and give you the desired results.