This issue is getting worse. Now it doesn’t appear to be saving team changes made in the Troops tab.
I can’t reproduce it reliably either.
At one point, the interface didn’t even show the correct data, corroborating what Mithran said about client/server issues.
For example, I had my Blackhawk defense team from last week. Using the same team slot (thus overwriting my Blackhawk team) I changed my defense team to a Pan’s Vale lineup and exited the tab. When I went to Explore, my invade team was still set to the Blackhawk lineup. So I went back to the Troops tab and set it to Pan’s Vale a 2nd time.
I then went into Explore and confirmed it stuck. I exited out of Explore and clicked on my icon in the upper left. I clicked on Battle! and my invade team was the correct Pan’s Vale team. However, my defend team was still the Blackhawk lineup which should be impossible given I overwrote that team.