'Other'-Option for multiple select checkboxes hide answers

Please check this webform: http://www.un-spider.org/webform/test-webform

The first question is a multi-select box 'listbox' with 'other' option, the 2nd question is a multi select checkbox, the 3rd a multi select checkbox with 'other' option active. Do you notice? No 3rd question. Exactly - that's the problem. All questions have the same answer options, but none is displayed on question 3. This means, the 'other' option on checkboxes hides the other result options. Is this issue known and any fix available?

Peter