Hi @DanP
Welcome to the MainWP Community.
As Bogdan explained in of the previous threads, the “Backup before Updates” feature is not fully compatible with the MainWP plugin. Basically, the UpdraftPlus doesn’t fire because it doesn’t detect that the update process has started.
As of right now, there is nothing on our side that could be done to change this behavior, but we are planning to revisit this and see if something changes in one of the future versions.