We published a map service using 10.6.1 ArcGIS for Server (on Linux) where the label is symbolised by concatenating 3 fields:
[Road_Name] + " " + [Road_Type] + " - " + [Road_Number]
When we use this as a Feature Layer in ArcGIS API for JavaScript version 4.18.1 (with npm build), the labels show up as the following:
That is, the word "concat" appears in the label, instead of "Prince Hwy - 0000001".
This issue does not appear if using Map Image Layer.
I tried various other ways e.g. using advanced functions, JScript / VBScript etc, no luck.
In addition, I tried to do the labelling in JavaScript code with LabelClass and labelExpressionInfo, the same issue happens.
I want to submit a bug report but there isn't an easy way to do so, hence the post here.
Can someone from Esri take a look please.