SQL Server Replication Local Subscription Properties returns "Cannot apply value ‘null’ to property ServerInstance: Value cannot be null."

I am replicating a SQL 2008 R2 database to a SQL 2016 database.

When I connect to the SQL 2016 database using SSMS, and in Object Explorer select Replication->Local Subscription->MySubscription then right click and select Properties I get the error "Cannot apply value ‘null’ to property ServerInstance: Value cannot be null.".

What does it mean and how can I fix it? I am logged in using my Windows domain user which is a sysadmin on both systems.