It’s a new caliper.
RS685 caliper do not have the best reputation (or was that the prior generation?) or possible 'flap' issue detailed here:
https://bicycles.stackexchange.com/questions/41573/shimano-rs785-hydraulic-disc-brake-caliper-will-not-reset
Yeah replaced with a deore, but that link looks promising though. Will investigate next week. Cheers.
@coventry_eagle started
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It’s a new caliper.