Measures in server-based Models

Dear all,

currently we are working on a PowerBI Model that is connected to a SSAS Server. We are using Visual Studio to create the columns and key figures that we then use to make up the reports. As there is so much data, we would prefer to use measures for some calculations, especially customer-specific ones. but the problem is, that since we use the server as datasource and no data-file, the option "create measure" is no longer available to us.

Is there any possibility to enable it again? Maybe by changing some setting or adding something?

Thanks in advance for your help!