Hey @Nadra
Welcome to the Klaviyo Community! Thank you for reaching out about troubleshooting your flow!
There are a number of reasons why an email was either skipped or still waiting. First, do you have Smart Sending turned on? If Smart Sending is on and the customer was sent a campaign or started another flow, they may still be “waiting” because of your Smart Sending settings.
Next thing to think about is if customers are being “skipped”. There are a few different skipped reasons and understanding those will help you determine what you need address. You can find the skipped reasons for a message in your analytics .
Also, did you add any new messages to the flow after it went live? If your customers exited the flow before the new messages were added, you can back-populate the flow which will add them back into the flow where they left off. Check out this other community post from @mermaidzeli on the same topic! @Taylor Tarpley response is great and includes additional community post that you may find helpful.
Hope this helps! Thank you for being part of the Klaviyo Community!