In our case, we used two tags, a custom tag and a tag underline provided by Ez. so we have an undeline tag included in the custom tag.
when we try to disable the underline tag by the button underline the other tag disapears (custom tag).

Steps to Reproduce:
To reproduce please follow the steps below, we provide here the xml data :

Origin:
Nos clients veulent qu'on leur simplifie la vie

Apply custom tag color:
Nos <custom name="couleur_orange" custom:orange="#FF6600">clients </custom>veulent qu'on leur simplifie la vie

And apply tag Underline:
Nos <custom name="couleur_orange" custom:orange="#FF6600"><custom name="underline">clients</custom> </custom>veulent qu'on leur simplifie la vie

Finally the Underline tag is disabled:
Nos clients veulent qu'on leur simplifie la vie

finally, My custom tag color disapears when I cancel underline tag.