When you release a investment project, you find the system automatically use the asset class 4001. You can't use your custom asset class.
SAP S/4HANA Cloud
Reproducing the Issue
Enter the APP "Project Control".
Create new investment project.
Maintain the parameters for your project.
The "Asset Under Construction ID" shows up automatically.
There is a standard content in cloud system, which demands you can only choose standard classes rather than custom asset classes.
It is standard behavior, you cannot use custom asset class when creating project for AUC.
Asset Class, Investment Project , KBA , FI-AA-AA-C , Transactions , How To