prepending after jump

RouterOS Forwarding Protocols
1

Hello.

Why following construction of filters does not prepend announces?
Generally, I want to announce nets from my-as list to isp1 with prepend=2

add action=accept chain=my-as prefix=x.x.x.x/x
add action=return chain=my-as

add action=discard chain=nothing-else
add action=return chain=nothing-else

add chain=filter-isp1-ipv4-out action=jump jump-target=my-as
add chain=filter-isp1-ipv4-out action=passthrough set-bgp-prepend=2
add chain=filter-isp1-ipv4-out action=jump jump-target=nothing-else
2

Place the prepend before jump. Once a prefix has been accepted, no more filter rules will be processed for this prefix