What does the little "on/off" switch do on the Di2 rear derailleur?  I just changed tubeless tires for the first time (think I got it right) and the Di2 manual says to flip that switch to "off" before removing the rear wheel.  So I did.  Oddly, the manual did not say anything about switching it to "on" after reinstalling the rear wheel nor was the switch in "on" position to begin with.

Put everything back together and flipped it to "on" to take the bike for a quick spin to help spread the sealant in the tires, and it wouldn't shift properly.  Got on line to try and self-educate but couldn't find answers.  Flipped the bike over to pedal and shift.  The RD would shift between 3 or 4 gears mid-cassette at best and would hesitate and struggle to go to larger cogs.  Out of curiosity I flipped the switch to "off" and everything works perfectly.  It looked like when it was in the "on" position that it was restricting the derailleur's movement and not letting it extend downward freely when I shifted to the larger cogs.

Anyway, working fine now.

Any insights?

Many thanks!