LAB: MIM2016 ADMA's failing to Refresh Schema against forests after the Exchange 2013 schema was applied

I have a production replica MIM integration lab with my source forest being Windows 2012 R2 \ Exchange 2013. My target forests where I am only using Outbound Sync Rules to push accounts are Windows 2012 and I just applied the Exchange 2013 schema update without having actual exchange servers in the target forests.

MY Target ADMA's do not have all the Exchange attributes available and Refresh Schema command is failing:

Retrieving the management agent data ...
Retrieving the management agent data complete
Retrieving the new schema ...
An error was encountered during the schema refresh. Please try again later.

I saw one post that recommended that the ADMA would need deletion and re-creation? Wouldn't that break all my Sync rules, workflows, sets, etc

any ideas?

-Stu