I think you have already figure out the solution from my other post. Pasting over here for completion:
Please check the is your system is running FreeBSD11 (OCCAM) kernel or Legacy (non-OCCAM) kernel. FTP with routing-instance is not supported on Occam based devices
Example:
start shell user root
root@e11-42:~ # what `which ftp`
/usr/bin/ftp:
FTP built by builder on 20180730.152300
feyrith.juniper.net:/volume/build/junos/occam/gcc/freebsd/stable_11/20180725.182919_builder_stable_11.2cd3a6e/obj/amd64/usr.bin/ftp <<<< this is ocaam
FTP release 18.4R1.8 built by builder on 2018-12-17 04:25:48 UTC
svl-junos-p001:/volume/build/junos/18.4/release/18.4R1.8/obj/i386/bsd/usr.bin/ftp << this is non-occam
You can use following method to do FTP via the instance:
show route forwarding-table table instance_name extensive | match "Routing table"
Routing table: instance_name.inet [Index 10009] < get the istance index
start shell
setfib -F 10009 ftp 10.219.57.21 <<< it will allow you to do ftp via routing-instance
PS: Please accept my response as solution if it answers your query. Kudos are appreicated too.