Problems with switching grid templates

[colin-young]

If I use

var TableTemplateRows = [
    " A A A B B B C C C D D D "
]
var GridTemplateRows = [
    " A A A A ",
    " B B B B ",
    " C C D D "
];

things work as expected and I can switch back and forth. If I change it to almost anything else, e.g.:

var TableTemplateRows = [
    " A A A B B B C C C D D D "
]
var GridTemplateRows = [
    " A A A A ",
    " B B C C ",
    " B B D D ",
    " E E E E ",
    " F F . . "
];

and now I can't switch. Usually what happens is the GridTemplate becomes unusable. I don't see any javascript errors in the console (like I do if I introduce an actual error). Is there some rule about how the templates need to relate to each other?

See fiddle

Thanks.

[tommedema]

I'm curious if this project was abandoned, seems like there is not much interaction lately.