Problem

Thanks, I had to apply above patch too (Drupal 8.7.8, NBSP 8.x-1.2, basic_html text filter)

Hey !! Many thanks for your help, could you please provide a patch to expose the main issue and be sure we never create a regression on this ?

The module has now tests, I don't understand how it does not works before ? LEt's see what's broken with the change you made and how we can improve the module !

Reroll the patch

The tests still pass, but they also pass without your fix :/ I'm kind of confuse could you please provide more context how to repeat the problem ?

It was a problem with the tests suites, may bad.

So the new code don't pass we have to see why and be sure we really fix something with the patch proposed and cover the case.

We had the same issue, the HTML generated was like this :
.....<span class="nbsp"> </span>....
So when the filter was replacing by inner child, there was nothing but a simple space character.

fixed on new release 8.x-2.2 (CKEditor 4 & CKEditor 5) and 3.0.0 (CKEditor 5).