Cannot Use Cure from "Additional Abilities" when playing as a THM.

[Hylphetien]

We appreciate you taking the time to report this error to us. However, there are still some details that we need to collect from you before we are able to investigate this properly. If you could please provide the following information, we will make sure that your report is looked into so we can try to resolve it.
*Can you please confirm which class you are specifically
*What additional slot do you have Cure in
*Where you in a Duty or Instance

[Mang]

We appreciate you taking the time to report this error to us. However, there are still some details that we need to collect from you before we are able to investigate this properly. If you could please provide the following information, we will make sure that your report is looked into so we can try to resolve it.
*Can you please confirm which class you are specifically
*What additional slot do you have Cure in
*Where you in a Duty or Instance

This, basically. If your Cure spell is placed in the far right slot on your Additional Actions, and you enter a Duty Finder or FATE that caps your level low enough to drop your total number of Additional slots by 1, it'll get pruned, so to speak. Additionally, once you equip the Soul of the Black Mage, you can use Physick, but not Cure.