Custom MyBatis Mapper not found in DbSqlSessionFactory MapperRegistry

Flowable Engine
1

Spring Boot 2.5.6 with embedded Flowable ProcessEngine:

<groupId>org.flowable</groupId>
    <artifactId>flowable-spring-boot-starter-rest</artifactId>
    <version>6.7.1</version>

Custom Configuration where various interceptors/handlers etc are set and also:

configuration.setCustomMybatisMappers(Set.of(MyMapper.class));

Interface exists and is Annotated

@Mapper
public interface MyMapper {

Trying to execute the mapper query

return managementService.executeCommand(
            commandContext ->
                CommandContextUtil.getDbSqlSession().getCustomMapper(MyMapper.class)
                    .findData(inputParameter));

results in exception

org.apache.ibatis.binding.BindingException: Type interface ctry.co.mine.MyMapper is not known to the MapperRegistry.
	at org.apache.ibatis.binding.MapperRegistry.getMapper(MapperRegistry.java:47) ~[mybatis-3.5.7.jar:3.5.7]
	at org.apache.ibatis.session.Configuration.getMapper(Configuration.java:845) ~[mybatis-3.5.7.jar:3.5.7]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.getMapper(DefaultSqlSession.java:288) ~[mybatis-3.5.7.jar:3.5.7]
2

Works when i declare the mapper through Properties

flowable.custom-mybatis-mappers=FQN for MyMapper