1) You should not use pin #26 for the Serial output control. It's only for output extension MUX.
You can assign any free controller pin as output for any number of serial drivers.
For example, you can assign pin #8 as output for one DM13A driver, pin #40 for 2x DM13A chained drivers, etc, as many as you need.
Not necessary to connect all as daisy-chained, even better if you will have separate drivers for every group of 16 LEDs (if you have free pins), and especially if these LED groups are located in different part of your panel.
2) Regarding the LED bar configuration, yes, I see that there is a bug in the configurator,
we will fix it ASAP.