Campaign stats "sent" count shows wrong value

[MaximilianKohler]

Version:

• listmonk: v6.1.0 (1b5e8d3 2026-03-29T13:18:16Z, linux/amd64)
• OS: Almalinux 9

Description of the bug and steps to reproduce:
This bug started after upgrading to v6.1.0 from v2.5.1.

I send daily campaigns to the same number of subscribers, and follow the same routine. Every campaign is sent to two lists, one with 3 subscribers, and the second with 2k subscribers.

1. Click the "clone" button next to the last campaign.
2. Rename the campaign, remove the list with 2k subscribers, toggle "send later" OFF, click "save changes".
3. At this point, you can see in the screenshot below that it shows "0" for all "stats" values on the campaign page.
4. I create a new list of 2k subscribers.
5. Add that list to the campaign, schedule the send.

Every other campaign it seems to be adding 500+ subscribers to the "sent" count.

Screenshots:
The first entry at the top with "0/0" is a draft, cloned from the previous campaign. Scheduled campaigns also show "0" for all values.

[MaximilianKohler]

Now the problem escalated to saying it sent 0/2k, as well as not sending to the full list. There are no errors in the logs.

2026/05/13 08:00:17.279398 manager.go:442: start processing campaign (xxx 2026-05-13 2k)
2026/05/13 08:00:17.293153 pipe.go:231: campaign (xxx 2026-05-13 2k) finished

Amazon SES stats show the correct values for every day. IE: On the days listmonk says it sent 2.5k, SES shows 2004 (2003 + confirmation email).

For today, when listmonk says it sent 0/2k, SES shows that it sent 327 or 328. I looked at the list of names & emails and there's nothing unique that stands out ~327 that might have caused listmonk to error. There were no blocklisted emails in list prior to the campaign being sent. 4 of them got blocklisted due to bouncing, and those 4 are spread out among the ~327 people who were sent the campaign.

I never experienced this with v2.5.1.

[MaximilianKohler]

Interesting... I made a brand new campaign (instead of cloning the last one) and it still stuck to the "+500 every other campaign" trend.