here is my setup
10.1.0.2 - Master (slave-priority 10)
10.1.0.3 - Slave (slave-priority 100)
10.1.0.2 - Sentinel1
10.1.0.3 - Sentinel2
10.1.0.4 - Sentinel3
The failover is working as expected when the Master is down. However, when the original Master already recovered it is not switching back to old Master.