I've seen this before. Try the following test to confirm my diagnosis:
Enter layout mode. select just the portal object, not any objects in the portal row and move it a short distance. Do both fields move when you move the portal? My guess is that at least one will not move with the portal. In my personal jargon, that means that the field is not "owned" by the enclosing portal object. To fix, drag the field away from the portal, release the mouse button and then drag it back, being careful not to let go unless the object you are dragging is fully inside the borders of the top portal row. Test by moving the portal to confirm that it now "owns" the object you just dragged. You can resize the field or other object to be extra small before you drag it and then use the inspector to alter it's position and precise position within the portal row once you are sure that it is now "owned" by the portal.
This "gotcha" has happened to me in the past when I placed an object outside of the portal and then used the inspector's alignment tools to move it into position inside the portal row. This puts the object where you want it, but the portal fails to take ownership of it. Thus, you have to drag the object into a rough approximation of where you want it and then use the inspector to fine tune its final position.
I will note that this quirk has on occasion, been a useful way to place an object such that it appears to be part of the portal, but really isn't.