Welcome to the forum.
You haven't done anything wrong except to not expect it. It's the nature of the beast(s).
Try moving the images themselves to a PC and putting them into your database from the PC platform. This works 99+% of the time for me.
I build on PC, but most of our Dbases were originally developed on Mac. When I come across a weird graphic, I:
- copy it to the Mac clipboard
- paste it into Powerpoint
- move the PPoint file onto a PC
- copy it from PPoint to the PC clipboard
- put it back onto the layout from the PC (and reconnect the function).
- then it typically is correctly rendered on both PC and Mac.
See if that doesn't work for you as well.
That makes a funny kind of sense in the strange world of PC-Mac compatilibility issues. I'll give it a try.
You could also try using Insert Picture instead of copy/pasting; using the clipboard to move graphics between applications is not the best way.