Counters remain on permanents, even if they don’t do anything.

If a non-creature permanent becomes a creature temporarily and receives a counter, that counter will remain even after this permanent stops being a creature. For example, if a is ‘animated’ by its activated ability and receives either +1/+1 or -1/-1 counters, those counters will remain on the Colonnade even after it stops being a creature. […]

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