Resolving Apex Class Access Issues
Real-time sync from Service Board to Salesforce is executed by using REST APis. For real-time sync to work properly, the Apex class, in which REST endpoints are defined, must be assigned to the integration user profile.
To resolve Apex class access issues:
• In the relevant profile, in the Apex Classes section, edit and assign the SB_Integration class, and then save the profile.
For more information: