We hit this issue with MRQ that I think is a new behaviour in 5.7. I can repro it on a new project (.uassets attached). If temporal samples is set to a high number, only the first child shot of a sequence will be written to disk. If I reduce temporal samples to like 3-4 then the other shots will get saved. See video attachment
Yeah, someone else reported this as well, and we’re circling around the appropriate fix. In the meantime, you can use the Movie Render Graph, which will just handle this issue behind the scenes. Alternatively, change your Sequencer tick interval to match your Sequencer’s frame rate per second (fps).