Text Inserted into Shapes Unexpectedly Disappears !!

 We are having a problem where text inserted into a shape mysteriously becomes invisible inside the shape (see the image below).  At one point, all the colored boxes in the left column had the numbers 1-6 displayed, just like the numbers in the right column.  When or why they disappeared is still a mystery, but they are definitely invisible.

The mystery is that the text is still inside the objects and can be viewed when the text is selected with the TEXT tool, as you can see with the number "1" in the top box.  But as soon as you exit, the number disappears again.  As such, we know the text is there and the black color does not match the shape fill, so that is not the problem.  Like the top box, the text in each of the boxes below becomes visible when selected with the text tool.

We have tried every way possible to get the text to display properly but cannot find the solution.  We have changed and reapplied colors to the text, removed and restored color to the shape, checked all object attributes and text attributes between the two columns, and can find no problem.  We have also checked the text size (no red marquee indicating it is too large for the shape), resized the shape, checked for inadvertent line returns, and other paragraph spacing issues.  Furthermore, we see no tools for ordering the text to the front or back of the linked shape.  It is as if the text is behind the shape fill, but deleting the fill or changing the transparency does nothing to expose the inserted text.

We would certainly appreciate any assistance anyone can provide regarding this frustrating anomaly!