Hey @AndyRussG, tagging you bc it seems relevant! We've got a test up in our en6C_dsk_FR campaign - I'm looking at buckets C & D. Two banners in each bucket and the impressions count for the banners seem suspiciously out of sync:
Bucket C:
Banner 1 impressions = 1,211,480 Banner 2 impressions = 1,214,810
Bucket D:
Banner 3 impressions = 1,178,290 Banner 4 impressions = 1,176,450