I’m not sure when the problem first appeared. I have done several upgrades of the Newsletter plugin (I usually apply each of your upgrades quite soon after you release them), and forgotten to check these settings every time, so I don’t know when the problem first occurred. I only noticed it on 5th April.
I’m currently on v3.2.1, which I installed about a week ago, but I can see that you have just released v3.2.2 a few days ago. Is it safe to upgrade to v3.2.2 now without losing my settings?