I had to do a sun study a while ago and I managed to make the one day sun animation using a custom technical viewport that I created especially for this. Now I had to revisit the project and make the same sun study on an updated design and it will just not work anymore. The render animation will either always switch to the default rendered viewport, or attempt to start a renderer (vray or rhinorender). I tried all options - RenderFull RenderPreview RenderedViewport Raytraced. There is no way to get the animation frames to stay in the Technicall view. I’m not sure if something got patched or if I got super lucky with unknowingly exploiting a bug last time, but that workflow does not seem possible anymore.
Another weird thing is if I open one of my old files and just hit record animation, it will run in the techical viewport and output frames with that viewport display as I initially intended. But as soon as i try and run the SetOneDay sun animation command again ( to change the day or anything), it will always swap to rendered viewport. abd i have not found a way to get it to output technical again after that.