Rendering accumulation in DELTAGEN stops working after switching from Stellar to Look to Stellar rendering and then switching object visibility in the scene tree.
Workaround: Deactivate the Global shadow Ambient occlusion (SSAO) in the Look rendering mode before switching back to Stellar rendering.
- check that you are in the Look rendering mode
- go to Render settings via Render > Settings or by pressing Shift + R
- in the Global shadow section, deselect the Ambient occlusion (SSAO) checkbox. Click apply.
- switch to Stellar rendering.
This issue will be fixed in DELTAGEN 2017x, released in November 2016.