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As of Oct. 27 the report now shows this message at the top left, and the report buttons are gone. I was able to run this report earlier in the week. Our roster has not changed, and we can pull up individual scouts and also enter activities.
I was able to duplicate this issue and have reported it to the developers.
The workaround is to use Scoutbook to get to the same report:
Login in to Scoutbook with your my.scouting.org ID and password.
Go to My Dashboard → Troop 809 → Troop Reports → Activity Log Report