Using ServiceTasks with TimerCatchingEvents in activiti bpmn workflow behaving inconsistently

[cloudnativeview]

When using ServiceTasks with IntermediateTimerEvents sometimes it did not execute the service task due to exception raised in ACT_RU_JOB table.

EXCEPTION_MSG_ column in ACT_RU_JOB table is populated with  "Unknown property used in expression: #{serviceTask1.execute(execution)"  as value for that particular job.

Please refer the activiti workflow image i have attached below for clear picture of the usecase.

NOTE: I am using spring-boot microservice using maven to run the workflow.

spring-boot version: 1.5.5.RELEASE
activity version: 5.22.0

Activity and Connection Pool dependencies in pom.xml:
<dependency>
<groupId>org.activiti</groupId>
<artifactId>activiti-spring-boot-starter-basic</artifactId>
<version>${activiti.version}</version>
</dependency>
Connection Pooling dependency:
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-jdbc</artifactId>
</dependency>

application.properties configuration attached below:
spring.activiti.job-executor-activate=false
spring.activiti.async-executor-enabled=true
spring.activiti.async-executor-activate=true

spring.datasource.tomcat.initial-size=15
spring.datasource.tomcat.max-active=100

ANALYSIS: The error i am getting above is not consistent.

Activiti Workflow Designed with Activiti Designer