Hello jf,
That message is unfortunately a generic Nuendo message, much like the famous -9173 message in PT. It can refer to VERY many issues while recording, not simply too many tracks. There’s probably something that is distracting Nuendo from it’s record task. I don’t know your Nuendo knowledge depth - have you done the usual stuff like checking the drive capability along with any network items? Are you running DropBox in the background or any other background access items?
I notice you mention a 4ms latency on the Dante Virtual Soundcard. The first thing I would test is up that to the maximum buffer setting and see how it goes. That won’t eliminate any background tasks you have going on but it will probably give you better results.
Hugh