If anyone is still having this problem with Corona v2, here are two things we would like you to try:
1) Make sure that the noise level limit is set to 0 - just select the value, and type "0" using keyboard. In some cases, 3ds Max may enter a value such as 0,002 in there, and it will be displayed as "0", but the rendering may still stop at some point, when the limit of 0,002 is reached. Once you are 100% sure that the noise limit is set to 0,00:
2) Use pass limit instead of noise limit - does the random stopping also appear when using pass limit?
Thanks in advance for any feedback.
Right now we unfortunately do not have any new findings regarding this. The issue is either too random, or system-specific.