Hello. I'm publishing an MXD from ArcGIS Desktop (v 10.8.1) to Portal for ArcGIS (v 10.8.1) so the map can be viewed on an iPad using ArcGIS Collector.
I have a multi-line label I'm applying to one of the layers. In the Portal Map Viewer in a web browser, the label is still single line when using TextFormatting.NewLine (no big deal), but it is correctly stacked when viewed in ArcGIS Collector. Unfortunately, though, the stacked label in Collector is center justified and it looks silly.

I tried adding some HTML tags to the Arcade expression, but no dice. This is the expression that creates this label:
$feature["MAINT_6_YR"] + TextFormatting.NewLine + $feature["NOTES_6_YR"]
Am I overlooking some text formatting options in Arcade? Is there some trick to get HTML tags to get this left justified?