SQL server backups in MABS V4 will not create initial replica

Hi,

We have various SQL servers and they backup fine in MABS V4 and have previous been upgraded from older SQL versions etc.

One of our SQL servers has refused to backup the DB's in MABS since it was upgraded.

We have recreated Protection Groups, set up a new MABS and still are unable to get it working again.

In MABS the DB job gets the below error/s:

The replica of SQL Server 2016 database SERVERNAME\DBNAME on SERVERNAME.DOMAINNAME. is inconsistent with the protected data source. All protection activities for data source will fail until the replica is synchronized with consistency check. You can recover data from existing recovery points, but new recovery points cannot be created until the replica is consistent.

For SharePoint farm, recovery points will continue getting created with the databases that are consistent. To backup inconsistent databases, run a consistency check on the farm. (ID 3106)

Change journal not initialized or is the wrong size (ID 30118 Details: The volume change journal is not active (0x8007049B))

The DB's are detected and added to the protection group but the initial replica is never created and is only 18MB for each DB.

DOMRACURR.errlog has some errors but they are quite generic, any pointers as to what might I might look at next? Can't roll back SQL or migrate to another server for quite some time so need to get this working as is.

SQL server 2016 SP3 CU1 running on server 2016.

Not sure if to look more at the SQL side of things, any pointers would be appreciated.

Thanks