There is very little activity with making starters, rarely do they bubble, even more rarely is there a krausen that we see. The only true activity that most of us see is just a creamy band at the bottom when it flocculates out.
Starters are some of the most "un-exciting" fermentations ever.
That one is cold crashed, but even if it is a t room temp, you should see the sediment in the bottom. I use a stirplate, but usually stop it a few hours early to let it settle.
Basically if you see a creamy band of sediment at the bottom, then it's done it's job.