I tried repeatedly. Try this test.

1 line yellow belt full both sides of coal, 20 long handed burner inserters.

In my game, I had about 1-3 of them just barely fail at placing the coal into themselves. By just barely i mean that if it went just a quarter of a second more, it would have succeeded.

I have found that sometimes the inserters don't have enough starting power to fuel itself. It gets so close before it runs out of power.