Strange "Create Empty Group" Behaviour

I'm working on an instrument that has many groups. Creating and working with new groups has worked as-expected up until now — selecting "Create Empty Group" would create a new sampler group that audio files can be dropped into.

Now, however, when creating a new empty group, Kontakt will create an empty sampler group, but when I drop samples into it, it creates another new group with the same name as the sample file, with beat machine selected instead. This leaves to manually created new group empty.

Does anyone know what might be causing this?

Thanks! 🙂