that helps. That was just a simple ffmpeg repackaging of the wtv container, so that works.
Which means something is breaking during the conversion process.
download hte latest beta version and there in the Conversion Task -> Expert Settings you'll find an option for Skip Remuxing.
CHECK that option and then run the WTV UNprocessed profile.
For now ensure that Commercial Removal is set to NONE, Write Metadata is NOT checked, NO Subtitle Extraction and NO download series information.
See if that works on your extender (trying to narrow this down).