Hello @AngelaB5 ,
Are you looking at Total Opens or Unique Opens? Your email's open rate will only reflect unique opens, not all opens, so that percentage won't be changing if the same people are regularly looking back at your emails. Additionally, updates to sent emails' reporting will diminish in frequency over time to avoid server overloads. For the first 48hrs, all data should be updating at least every 10-15 min, then after the first week it'll begin updating less frequently. It will, however, continue to track that info as long as you have an actively paid account.
See also:
Email reporting overview
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