Steps to reproduce
Set up the issue type mapping incident and service request (project A) to incident (project B)
Set up the issue type mapping incident (project B) to incident (project A)
Set up comment synchronization bidirectional
create a service request in project A - this will create a incident in project B
Leave a comment in project B
the comment gets synced to project A, which remains the issue type service request
the comment gets synced to project A but the issue type gets changed to incident.