The number of layers that can be registered for each image maker and each part is limited.
The maximum number of layers that can be added for one image maker is 50.
You will not be able to add parts or layers if you reach the limit.

Limit for each part type

The maximum number of layers that can be added differs according to part types.

Type	Number of layers
Standard Part	Up to 5 layers
Left-Right paired Part	2 layers（Cannot be added or removed）
Last Bastion	Up to 5 layers