You are right. I have fixed a problem perhaps related to this problem ... but anyway the main problem is that it seems a limitation of Houdini. I am testing a scene rendering two chained Mantra ROP nodes, one with a 5 frames range and other with 10 frames range, and both are rendered using the 10 frames range. If use the merge node I also get the same behavior.
Can you please check in your system if Mantra has the same problem, to be sure? I am testing H15.0.393
Computer Graphics Software Developer
Octane plugin development and support: LightWave and Houdini