Monsters Not Entering Scene Correctly

Hoping someone can offer some help on this strange new behavior.

Moving monsters from my Actor Directory to a Scene is giving me different results. As you can see in the attached image the Crystal Drake has loaded in just fine (It placed their token, rolled initiative and HP dice, and it’s ready to go for the encounter) but when I tried to add a Cockatrice (which I had previously successfully used in exactly the same way) I got a pop-up box with “What type should this actor be created as?”

I’ve not had this happen before and as I’ve investigated it, it’s doing it with the vast majority of my monsters (and sometimes, even the Crystal Drake that worked in this instance).

Any ideas on what this is / how to fix it?