"Invalid interface" counter is incrementing on all FPC:

root@router-re0> show pfe statistics traffic
<SNIP>
Packet Forwarding Engine hardware discard statistics:
    Timeout                    :                    0
    Truncated key              :                    0
    Bits to test               :                    0
    Data error                 :             76762540
    TCP header length error    :                    8
    Stack underflow            :                    0
    Stack overflow             :                    0
    Normal discard             :             25095956
    Extended discard           :          22113581663
    Invalid interface          :               859244   <<<
    Info cell drops            :                    0
    Fabric drops               :                    0

Multicast enabled PTX.
"Invalid interface" counter increase rate and value is matching dlu.ucode.ip_mc_iif_mismatch trapcode under PFE command shell:

root@root-fpc4:pfe> show cda trapstats
<Omitting irrelevant trapcodes>
Trap Stats:
DEV        TRAPCODE   NAME                                                       COUNT          RATE
 2          17         dlu.ucode.ip_mc_iif_mismatch                               96282          0
 3          17         dlu.ucode.ip_mc_iif_mismatch                               85954          0


There are interfaces with mismatch counters increasing (in multicast statistics).
Also there are multicast routes with "Wrong incoming interface" counter > 0.

user@router-re0> show multicast statistics inet interface ae11
Instance: master Family: INET
Interface: ae11.0
    Routing protocol:          PIM   Mismatch error:               0
    Mismatch:               205035   Mismatch no route:        14965
    Kernel resolve:         515517   Routing notify:               0
    Resolve no route:            0   Resolve error:                0
    Resolve filtered:            0   Notify filtered:              0
    In kbytes:        219934506147   In packets:        165941765690
    Out kbytes:                  0   Out packets:                  0

user@router-re0> show multicast statistics inet interface ae22
Instance: master Family: INET
Interface: ae11.0
    Routing protocol:          PIM   Mismatch error:               0
    Mismatch:               175136   Mismatch no route:          642
    Kernel resolve:         302604   Routing notify:               0
    Resolve no route:            0   Resolve error:                0
    Resolve filtered:            0   Notify filtered:              0
    In kbytes:             2062279   In packets:             1555825
    Out kbytes:       219538880345   Out packets:       165643296367


user@router-re0> show multicast route extensive | match "Wrong incoming interface" | except ": 0"
    Wrong incoming interface notifications: 1
    Wrong incoming interface notifications: 1
    Wrong incoming interface notifications: 1
    Wrong incoming interface notifications: 1
    Wrong incoming interface notifications: 1
....