This is not the point. The reply packet is of no interest. The forward packet is not forwarded but dropped on the EX4200.
Reply packets do not create ARP entries. ARP replies do. And the arp reply is sent to the correct MAC address.
So the EX4200 receives the ARP reply within 30ms and - proof - it is shown there by the CLI command.
1) packet to destination .44.83 is received by EX4200.
2) ARP request is broadcasted
3) ARP response is sent back
4) EX4200 has ARP entry
5) this packet _to_ .44.83 is not seen on the target host. (dropped)
6) next packet to destination .44.83 is forwarded, received by target, and (yes, asymmetric) replied.
The reply is nice, but is not the issue here.
I got a EX3200 to play with yesterday. Unfortunately I'm on vacation next weed ;-) but then I will rebuild this here in office with minimum settings. I'm really wondering that not all of us are effected by this really annoying behaviour.
br
Walter