Why did Klaviyo skip my abandoned-cart email after the customer received my welcome email?

Most likely, that was an intentional Smart Sending skip, not a broken abandoned-cart trigger. Klaviyo’s default email Smart Sending window is 16 hours, so a recent welcome email can make the cart email skip if Smart Sending is on for that message. Open the abandoned-cart email in the flow, then Performance > View details > Recipient activity > Skipped—the listed reason is the thing to trust. If it says Smart Sending, decide whether that frequency limit makes sense for this particular cart email; if it says Fails Flow Filters or Fails Additional Filters, check those at the time the message was due. Also make sure the person didn’t place an order, since that normally removes them from an abandoned-cart flow. Don’t switch off safeguards until you’ve confirmed the reason, though—you don’t want to trade one skipped email for a pileup of marketing emails.