No ack everywhere

I use Indigo 2023 2 on an iMac M1. I have around 20 Z-wave devices. Over the past weeks I get random no ack messages from different devices. If I switch them on or off anyway, they respond normally and the red no ack messages disappear. I do not have to exclude and reinclude any device. Could it be a malfunctioning USB stick (AEOTEC ZW090)?

[jay (support)]

I'd first try running a network optimization (from the Z-Wave interface menu). Do it over night as it could take a while.