Are you doing NBU-scheduled backups or are you triggering them from the client ? If you're having NBU kick off the backup job then I can easily see it getting confused about which schedule to use since you only have a single policy - that's a known issue with any database policy and why you should only have a single retention in those.
If you're doing client-side triggered jobs that's a different story, you ought to be able to get away with a single policy for multiple retentions since you're specifying the exact schedule name to use.
Please confirm which method you're using.
