Yeah weird, in the end this definitely shouldn’t be happening - for the most part I think FME usually ignores types except for readers and writers. 

Are you 100% sure that it’s the join that’s the issue?

I would double check by throwing down some loggers before the FeatureJoiner to make sure that the data are actually there. 

If you can confirm in your logs the values are the same then that would be really weird. Does the behaviour change if you switch from Automatic mode to something else?

Thanks Matt,

I added loggers and ran in Form. I get this (changed value 2 to 6, doesn't matter):

2025-06-06 14:02:17|   2.4|  0.0|INFORM|Logger: Choice Class is: 6
 

When published to Flow is logs:

2025-6-6 14:00:16 | Logger: Choice Class is: "6"

So it had quotes around it and thus doesn't join in the featureJoiner/Merger.

I put a stringreplacer between to remove the double quotes on both sides and then it does work. Personally I really don't understand this behavior. Could this be caused by different settings on Flow? Kinda new to that.

I added a debugging workspace and las file for testing.

Hi ​@fdw ,

I was able to reproduce the issue with your workspace, FME Flow 2025.0.2.

I have inserted another Logger immediately after the Creator, select two classes, and run. The Logger logged:

Attribute(string: UTF-8) : `CLASSES' has value `"6"."2"'

I think it’s a kind of bug, would recommend you to submmit this case to Safe support.

https://support.safe.com/hc/en-us/p/Support

Thanks ​@takashi 

I will send in a support ticket.

This does appear to be a bug. I've filed a ticket with our development team (FMEFLOW-25712). The StringReplacer as you mentioned should work as a workaround for the time being.