I'm using NDFileHDF5 ver. 1.10.1 with ADCore 3.10.0 and areaDetector-master. SWMR mode is set to "on", the "flush on N'th frame" field is set to 1, and "frames cached per chunk" is set to 1. When write mode is either set to "single" or "stream" with # capture set to 1, the saved frame is filled with the "fill value" parameter. When I turn SWMR off, both the "single" and "stream" modes save a single image frame correctly, as expected. The problem goes away when >1 image is saved.