@shahidIqbal could you clarify what you mean by 791 eligible customers ?
Is it customers that have the date_of_birth field set? have you created a Klaviyo Segment with that condition and gets the same count?
I also cannot ascertain whether the fields themselves are in the correct accepted Klaviyo formats as prescribed here:
https://help.klaviyo.com/hc/en-us/articles/115005253428
@shahidIqbal, a few questions for you
1. can you confirm the format you’re using for this date_of_birth property
2. can you confirm whether this problem only impacted 10/25 sends? Or has it impacted all bday sends 10/25 and after? The profile filter of “Has not been in flow in last 364 days” looks suspect to me.
3. What else is in your flow after the conditional split?
Hello @shahidIqbal
Thank you for reaching out and sharing the screenshots — that helps a lot!
From what I can see, this issue isn’t a bug — it’s actually how Klaviyo works with birthday flows. Even though your customer list shows 791 people with birthdays on October 25th, only one person entered the flow because Klaviyo only triggers it for profiles that meet all the right conditions.
Here’s what might be happening:
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🎂 Some customer birthdays may be saved as text (like “10-25”) instead of a proper date (like “1990-10-25”) — Klaviyo only triggers birthday flows when it recognizes the date format correctly.
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⏰ The flow is set to Asia/Tokyo time, so customers in other time zones might not have been triggered yet.
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🔁 The filter “has not been in the flow in the last 364 days” could be blocking some who already got their birthday message last year.
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🧩 Some profiles may not have their date_of_birth property synced properly from Shopify or your customer database.
✅ Here’s how to fix it:
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Check that all birthdays are in the correct YYYY-MM-DD date format.
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Try removing or adjusting the “has not been in flow in the last 364 days” filter to test.
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Confirm that your trigger is set to “On date property” and repeats yearly.
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If needed, re-import your birthday data with the correct format so Klaviyo recognizes it properly.
Once these are corrected, your birthday coupon flow will send automatically to all eligible customers on their special day! 🎉
👉 If you’d like, I can walk you through how to quickly check and fix the date formatting so everything runs smoothly next time — would you like me to show you how?
Warm regards,
Stylo Global Expert
@Stylo Global @whereisjad @cadence
Thank you very much for your detailed answer and the time you took to help me.
Based on your answer, I investigated further and found that my date_of_birth values are stored in two different formats — some as "1980-07-03T00:00:00Z" and others as "1980-07-03". It might be related to a timezone issue. I’ll remove the timezone from the Flow and continue monitoring the results.
Once again, I truly appreciate your guidance and support.
