Nuendo 6.5.20 Build 174
If you hit the “Bypass all Inserts” button it works as expected.
Hit it again and it toggles them back to active.
BUT if the plug-in on slot1 is one that can’t be loaded f.e “!!! MonoDelay” all the following plugins on slot 2, slot 3 … don’t toggle back to active but stay in bypass mode.