Answered: Tooltip gets truncated, wraps to next line.
In my login form, a tooltip wraps to two lines, but not enough space is provided, so the second line of the tooltip is cutoff.
Often the tooltip shows fine, but if I do a browser zoom (Ctrl + + or Ctrl + -) then the issue appears, though there is plenty of room to display the tooltip.
Posted by glafrance
This post provided by the support team indicates zoom is not supported in ExtJS, especially in IE: