Did you accidentally to turn on the
--skip-band-alignment parameter? That might cause this.
I don’t have a Sentera 6x, but I do fly a MicaSense Altum. Since the Sentera also has separate cameras, a single exposure needs to be co-aligned during processing. As far as I can tell, ODM currently can’t handle stacked tiffs. There are some examples on this forum combining separate (non-stack) tiffs for each single exposure.
To me the ODM radiometric correction model is still kinda opaque. But if all you need is RGB, you could perhaps align/crop/undistort etc in Sentera provided software and then use ODM.