zombonline I think Spinebot's mention of Cull Transparent Mesh was a good insight, but I believe it should have also mentioned the following: There are two ways to hide specific parts—deactivating the attachment, or setting the slot color alpha to 0 to make it invisible. As a general rule, in the former case the attachment will no longer be drawn, while in the latter case it will remain part of the render process. This distinction is explained in the following section of the user guide:
https://esotericsoftware.com/spine-slots#Color
Fortunately, for spine-unity, transparent attachments are no longer rendered starting from version 4.2-beta. If you are using a runtime version 4.2 or later, this should not be an issue.
https://en.esotericsoftware.com/forum/d/17328-are-attachments-rendered-when-slot-color-alpha--0
Since you mentioned that “only some parts” of the transparent area register clicks, I suspect you might be using an older spine-unity runtime and are hiding parts by setting the slot color alpha to 0, which could explain the inconsistent behavior.
If you want to define a hit area independently of the mesh, the bounding box attachment is often used for that purpose. After setting it up in Spine, you can use the BoundingBoxFollower component to assign that shape to the PolygonCollider2D. (It’s typically used together with the BoneFollower component.) This can be helpful when you want precise control over hit detection.
