How are you trying to view them on the iPad? Are you tapping the Attachments tab on the action editor? Does the attachment show up in the list there? How are you attaching the images to the actions? I would try the following sequence of events:
- Create a new test action on the iPhone
- Sync iPhone
- Sync iPad
- Verify new test action has appeared on iPad
- Attach image to test action on iPhone
- Sync iPhone
- Sync iPad
- Rename test action on iPhone
- Sync iPhone
- Sync iPad
- Verify test action has been renamed on iPad
- Edit action on iPad and try viewing attachment
This long sequence ensures that there is an actual attachment (rather than a link, which you might get if you built the test action on the Mac) and that all transactions involving that action have been successfully synced to the iPad.
If it still isn't working, you might try rebooting the iPhone in case it is a memory issue. I have seen some peculiar behavior when memory is low, and the iPad has disappointingly little of it, IMO.