1 - Try changing the objects y position from the top of the page (make sure it is not negative).
2 - Have you checked if the active/inactive colors are able to show the font colors appropriately (are they both dark font colors, so that it will contrast with the white and you will confirm the ability to see it).
3 - Have you moved the object lower than its current position?
There have been some issues with few functionalities in AJAX. Which version of qlikview are you using?
In your case, it looks like the color of the caption is the issue. It might display properly on some browsers and might not on some.
You can try the following:
1. Try changing background color of the caption and check once. Might be of help.
2. Try changing color of caption's font. This will help in determining whether the entire caption along with the text is not displayed in IE or just the caption. (Since font is white right now, so can't see the font either)
This does look like a known defect. Object captions appear transparent in IE9 (should work fine in 10 and above). It's caused by the use of gradients in the caption color. Either wait for the bug fix (should be out in the next SR) or use a solid color instead as a workaround.