When using DVCC the MPPT and DCDC algorithm is disabled for the GX/Venus device.
What happens when the Controller is offline? Does it stop charging entirely or does each charge source revert to internal algorithm?
It is also going to depend in part on hwo the system is programmed - ess or not?
With DVCC off it already follows its own internal charge logic under certain conditions.
You can always self test by unplugging the mppt to check what happens in your proposed scenario.