Can you share the below.
root@SRX> show route "source IP from where you ping"
root@SRX> show route forwarding-table destination "source IP from where you ping"
Now execute the below and check.
root@SRX# deactivate interfaces reth1
root@SRX# deactivate interfaces reth2
root@SRX# commit full
Then test ping to reth0.