Quick Search Prompt Limited to Four Characters?

I have created a Quick Search which includes both a Prompt and a drop-down Value list. My preference would be to have the drop-down below the text prompt, but there appears to be an unusual four character limit in the Prompt text box when it is in the top position.

I worked with an Epicor developer on this, and he was quite surprised to see this behavior. He then had me delete the Prompt and re-create it, which placed it in the bottom position, and I was then able to type as many characters as I wanted. Later on, I decided to delete the drop-down Value list, and re-created it, placing it back on the bottom position, but the four character limitation returned, and I haven’t been able to get it back to unlimited text since.

Has anyone else experienced anything like this?