Can't put zeroes in tables???

This table should have zeroes "0" on the diagonal from top left to bottom right.

	1	2	3
1		1	2
2	1		1
3	2	1

And yet when I preview it or post it, those cells are empty.
When I inspect the BBCode before posting, the "0" characters are where I'd expect them to be. The full table appears as thus

Code:

[xtable]
{tbody}
{tr}
{td}0{/td}
{td}1{/td}
{td}2{/td}
{td}3{/td}
{/tr}
{tr}
{td}1{/td}
{td}0{/td}
{td}1{/td}
{td}2{/td}
{/tr}
{tr}
{td}2{/td}
{td}1{/td}
{td}0{/td}
{td}1{/td}
{/tr}
{tr}
{td}3{/td}
{td}2{/td}
{td}1{/td}
{td}0{/td}
{/tr}
{/tbody}
[/xtable]

But if I go to edit the post after having posted it, the bbcode for the table has changed to this.

Code:

[xtable=skin1]
{tbody}
{tr}
{td} {/td} 
{td}1{/td} 
{td}2{/td} 
{td}3{/td}
{/tr}
{tr}
{td}1{/td} 
{td} {/td} 
{td}1{/td} 
{td}2{/td}
{/tr}
{tr}
{td}2{/td} 
{td}1{/td} 
{td} {/td} 
{td}1{/td}
{/tr}
{tr}
{td}3{/td} 
{td}2{/td} 
{td}1{/td} 
{td} {/td}
{/tr}
{/tbody}
[/xtable]

 

⁣0⁣⁣	1	2	3
1	0⁣⁣	1	2
2	1	0⁣⁣	1
3	2	1	0⁣⁣

The forum is using 0 for null in this case? You could experiment with invisible unicode characters. Non-breaking spaces don't seem work, but the "Invisible Separator (U+2063)" appears to. I put one after each zero. It probably increased the column width by one character, but it's not noticeable.

I looked at this in Chrome, Firefox, and my Android phone and it worked for all three.