Paul, your answer may be below.
My wife has no idea that I started this thread (as well as many others ..LOL)
I'm at work, and my wife just called me.
She tells me that she took Kira for a 2 hour walk today. Along the way, she met with a neighbor around the corner. The neighbor has a 2 yr old female WGSL named "Zena". Zena is a calm, very playful GSD. Kira has played with her in the past, without issues.
My wife invites the neighbor to go for a walk with her. They're all walking together, side by side, and about 10 minutes into the walk, Zena goes after Kira. (Both leashed, so no harm).
I asked my wife if she had any idea why Zena suddenly changed her love for Kira, and she said that the Zena's owner noticed a slight snarl from Kira, as they were walking. (Kira showed her teeth).
She said Kira instigated it.
Both women corrected, and they were OK.
This may be what I'm not seeing.
My wife just ironically sent me a picture of her and Zena hanging out together.
This is the closest I've had Kira next to another dog in a while.
They were chewing a stick together.
(Kira on left with the choke collar)