Grid Poll on Site view is shown as 4 options instead of two

When I create a 2*2 grid poll in frontend it is only shown as 4 options (option1, option2, column1, column2) on the backend poll view.

Casting a vote on a 2*2 grid with result showing afterwards hangs => The loading.. symbol keeps on turning.
The status bar shows the page error symbol. Clicking on details brings:
polls
line 51
char 21
Error: 'length' is null or not an object