Simulink Data Inspector: Too many outputs requested. Most likely cause is missing [] around left hand side that has a comma separated list expansion

Hi all

Using the data inspector of Simulink I run into a problem when I like to add or remove a signal to be streamed to the Data Inspector. Always, the following error message appears: Too many outputs requested. Most likely cause is missing [] around left hand side that has a comma separated list expansion.

Has anyone an idea what I can try to fix it?

Thanks a lot in advance!