Re-engage campaign. Email did not sent to everyone

Your software
My Mautic version is: 3.1.0
My PHP version is:

Your problem
We started our re-engage campaign but the first email did not sent to everyone.
There are several step where it exclude other segments and tags, but it collected in total 62494 emailadresses that the first email should have sent to.

After 8 hours it had only sent to 9.
Today (the day after) it has now sent to 5403.

We have two separate campaigns, since we are testing the re-engage campaign on two of our segments before implementing it on everyone. But it is the same email.

Before sending the email, everyone who was cleared for receiving it has been given ‘re-engage’ tag. There are 62494 with the tag - but still only 5403 who has received the email.

Screen shots from the campaign

Screen shot of results
1st campaign
52951 should be ready to receive the email

2nd campaign
9566 should be ready to receive the email

These errors are showing in the log:
No errors in the log

Steps I have tried to fix the problem:
Nothing yet, it started sending out more on its own.
It is set to be an marketing email - can that cause issues?

The sent out day is fixed to Tuesday - what happens now that we passed that day but it did not sent to everyone? Will it wait till next Tuesday and try again?

Next email in the campaign it scheduled to 4 days after.