Providing you used the 'rollback' button on a single network as below, you're correct in that this should have only rolled back that single network in the batch:
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As for it displaying the fact that this is rolling back all networks in that batch, this is unfortunately a known UI-only issue on our side 😟. The dialog will state that all networks are rolling back, but the action will only roll back the selected network.
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Hopefully helpful!
Whilst I am a Meraki employee, some of what I post may be opinion (especially architecture!). Others may have better or more efficient ways of doing things, so please learn from everyone!