QA403 output on my oscilloscope

New to the QA403. I’m looking at the output of the box on my scope and I get the sine wave I expect but also a rapid flashing signal of graduated amplitude at the same time underneath the main plot.

Also the VRMS of the output is not constant as I would expect from a standard sig gen.

Anyone have any idea on what this is and how to stop it???

Try to click on the button idle - same result?

See this thread