Scene length is 240 frames and it seems to bail out at frame 170 with a few odd large cache files. Log enclosed :
reactions.zip (69.4 KB)
R21 seems to, well has simmed all 240 frames but though they render they do not show in the viewport until rendered. I mean the default shading. R21.zip (21.0 KB)
R23 seems to have done the sim AND shows the shading in the viewport which makes for longer sim times…swings and roundabouts !! reactions23.zip (20.3 KB)
The large cache files might be from when you paused the simulation and jumped to a different frame?
If you have velocity caching disabled, Reactions will still store the velocity to cache if you interrupt the simulation. This ensures that you can later continue the simulation from the last simulated frame rather than having to re-run from frame 1.
I wasn’t able to reproduce these viewport issues in R21. Note there is a Known Issue with the far clipping in the viewport in any C4D version. This causes the volume to clip much earlier than expected when the camera moves away from it.