Do you mean that “Rollback complete payment” option is not avaialble? This is the option to do full rollback of supplier offset. Partial rollback makes no sense here. 
 

Sorry, Did I say a partial rollback?

I have a supplier offset which has matched invoices with a SUPOA.  It now looks like these were incorrect and I would like to match correctly to reconcile the account, but I cannot see anywhere that I can unmatch the offset to leave the SUPOA and invoices open

Use Rollback complete payment option.

Use Rollback complete payment option.

Is there a reason why that option wouldn’t be available?  I can see it available for Offsets processed this current period, but I am trying to cancel one from a previous period/FY?

For Supplier payment, this option is not available if transaction is reconciled/matched with bank statement, but for offset case there is no bank account connected - this should not block rollback. 

As far as I can tell, if no access restrictions in place, supplier offset rollback option should always be available.

Can you see the option and it's greyed out or you can’t see it at all? Is this option available for other supplier payments?

all resolved now, when I revisited this I was able to reverse the offset.  Maybe a glitch when I first looked