Repacking RDS database with pg_repack isn't online
We found a similar issue. The issue appears to be that log tables created in the repack schema don't have the correct permissions. Our solution was to use ALTER DEFAULT PRIVALEGES to fix this:

CREATE EXTENSION pg_repack;
ALTER DEFAULT PRIVILEGES IN SCHEMA repack GRANT INSERT ON TABLES TO PUBLIC;
ALTER DEFAULT PRIVILEGES IN SCHEMA repack GRANT USAGE, SELECT ON SEQUENCES TO PUBLIC;