Hi Crispino Alexandra, I know how frustrating it is when you set up a flow that looks perfect but the email step just doesn’t fire it feels like you’ve done everything right and still hit a wall.
Instead of relying on SharePoint calculated column calculate the days left inside your flow using dateDifference compare as numbers with int() keep the email action inside the True branch of the loop and optionally pre filter items by date for better performance.
Which column holds your contract end date in the list, and when you ran the flow last what exact value did the dateDifference/Compose step return for one item you expected to email?
Best regards
Lucky