Hi,
It would be failing in assymetric routing, you can check in the debug flow basic. You can try "set flow reverse-route clear-text prefer" as in the KB https://kb.juniper.net/InfoCenter/index?page=content&id=KB19924 . Please note it's global command.
KB for debug flow basic : https://kb.juniper.net/InfoCenter/index?page=content&id=KB12208
Thanks,
Vikas