With 16.3.7 it's the same. Sometimes (e.g. 30% of our stacks) physical ports are up, but logical port-channel is down after reboot.
'show etherchannel 1 summary' shows everything is fine (SU).
Workaround with 'shutdown' and 'no shutdown' lets the port-channel become up.
We used EEM for reset uplink interfaces:
# conf t
(config)# event manager applet SHUT_INT
(config-applet)# event cli pattern "shut_po1" enter
(config-applet)# action 1 cli command "enable"
(config-applet)# action 2 cli command "configure terminal"
(config-applet)# action 3 cli command "interface Po1"
(config-applet)# action 4 cli command "shutdown"
(config-applet)# action 5 cli command "no shutdown"
(config-applet)# action 6 cli command "end"
(config-applet)# end
# show int desc | i Po1
Po1 down down
# shut_po1
# show int desc | i Po1
Po1 up up
# wr mem
