In certain scenarios under an IP fabric it is possible to encounter traffic disruption problems within the same fabric, this only in certain leafs.
Over the logs you will se the following error:
root@juniper> show log messages | match array
Apr 22 11:25:52 juniper fpc0 bcm tx array failed Invalid port count 1
Apr 22 11:26:03 juniper fpc0 bcm tx array failed Invalid port count 2
Apr 22 11:26:04 juniper fpc0 bcm tx array failed Invalid port count 2
Once these errors have been found, they are due to BCM transitive errors and in most cases they can be solved with a reboot of the leaf, in case they persist, proceed to open a case with JTAC for further analysis.