Photos syncs the wrong time period of photos to iphone

Hi,

I recently upgraded everything to the latest software (Iphone, ipad, mac) and now I have bizarre photo syncing problems.

- Iphoto was migrated to Photos, ok

- I try to sync ONLY the last 1 month of pictures

- In Itunes I select sync only selected albums and then check NONE of them

- I select automatically sync last 1 month

- After sync, the Iphone then has the last month plus a random selection of photos going back 4 years. Not all photos, just a completely random selection of about 300 extra old photos.

- The photos themselves are dated, say 2004 in both mac photos and the iphone (its 2015 now) so the dates on the photos are not wrong. I have looked at the individual photos in mac photos and there are no weird metadata tags

- I have repaired the Photos library, deleted the Photos Ipad cache, etc

- I can use sync to remove all photos from the iphone, so they are imported via sync (I can't delete them from the iphone itself)

- If I don't use the 'automatically import photos from last month' check box, I can successfully sync only some selected albums without the random old photos appearing, so its certainly an issue with the auto import last month feature

- I have tried syncing all options from last 1 year, 1 month, 1 week and the problem persists

- Each time I try a different sync or fix, its the same set of random 300 ish old photos that keep appearing on my iphone

I am totally confused. Any ideas out there?

Thanks,

Matt