New line labels not stacking in Map Viewer Classic

[hherrmann_coj]

Edit to admins: This should probably be in Portal questions but I don't see a way to move it.

Hello everyone.  I am working on a map in our Portal so I can build a web application for a project we have coming up.  For some reason, I am able to successfully use the following expression to stack two fields in the label in Pro, but not in Map Viewer Classic.  

Expression:
"MM" + " " + $feature.trl_mm_numb
+ textformatting.NewLine
+ $feature.comments

Result in Pro:

Result in Map Viewer Classic (in Portal)

Any ideas?

[KenBuja · Accepted solution]

The Map Viewer Classic uses the JavaScript 3.x API, which doesn't support NewLine. The new Map Viewer (built with the JavaScript 4.x API) does support NewLine.

[hherrmann_coj]

That feels much like being forced to use Pro over ArcMap because upgrades and support will be ending eventually.  I'm not a fan of the new Map Viewer yet for similar reasons that I'm not a fan of Pro yet, although I am forcing, begrudgingly, myself to use Pro.  LOL!

Thank you so much for your feedback though.  I appreciate it and "reckon" I'll go open my map in the new Map Viewer, sadly.  LOL!