I’ve also seen the same issues with being unable to set a bike to red, the two ends of the spray can slider for me are “orange” and “pink”. I’ve seen this on all the bikes I own that support the spray can from memory that’s the following:
- Canyon Aeroad, Inflite & Ultimate (even if it’s only the SRAM red Etap highlights on the shifters)
- Cervelo P5
- Scott Spark RC
- Specialized Allez
- Zwift steel, carbon, aero & TT
The only bike I own that actually appears red (bottom of the slider) is the Zwift MTB