For the system to create an entry in the events when the account is placed on Stop, there needs to be a Controller on the Customer Tab, so that the system knows where to send the follow up to.
To check this:
Go into Sales Ledger or Purchase Ledger.
Find the Account the query is for.
Click on the Customer Tab.
Check the details in the Controller Field.
If there is no controller this will be why nothing is saving to the events.
Update the Controller Field with the relevant Controller Code.
Then going forward when the account is placed on or taken off Stop this will show in the event log.