Hi Alan,
Well this is the first time I’ve seen a plot of delta UMa myself. VSX says the variability is of unspecified type, but this link suggests a possible EB http://liber.onu.edu.ua/pdf/astro/all/OAP_9/000_pdf/bryukh.pdf
It’s quite interesting that the amplitude of the fades vary from one fade to the next. Be nice to see a much longer plot. My eyes are possibly seeing a secondary wave on that light curve.
Gary