Which attribute are you converting? What does the input look like?

Sample table above, suing the transformer to convert into the format on the right

If you look at your screenshot, everything is exiting the DateTimeConverter from the Rejected Port.

Can you share your settings, it's not doing what you want it to do.

If you have null values in your data, you need to make sure Passthrough nulls, empties or missing is set to Yes

And, as @ebygomm​ said, how have you set up your DateTimeConverter? The input looks like it can be autodetected and the output isn't too tricky either. %Y%m%d as input and ISO date as output should work.

I am going to jump aboard this community post with my screenshot of a similar issue.

I can’t work out why this simple example is getting rejected. I want to read in the date value %d%m%Y and convert it to another date format (in the example above I have used %Y for simplicity/testing).
The Preview Data within the transformer behaves as expected but the transformer rejects it.

Version: FME(R) 2023.1.0.0 (20230825 - Build 23619 - WIN64)

Hi @badgerseatfrog1:   I’m sorry you’ve come across an issue with the DateTimeConverter.  I was able to reproduce this issue. I’ve created a ticket for our development team to look at (internal reference FMEENGINE-82492).  We’ll keep you posted on any updates here.