The failover does not seem to work for toColor in 7.5.4.

This works fine:

toColor({Root}[{Root Container.lotWrapCode.selectedRow},"ColorCode"])

This does not:

toColor({Root}[{Root Container.lotWrapCode.selectedRow},"ColorCode"],"black")

Did you get an error when using the failover? It looks like that expression isn’t casting the failover as a Color when returning it, I’ll put in a bug ticket for this issue. You can cast that string as a toColor() as a workaround for now:

toColor({Root}[{Root Container.lotWrapCode.selectedRow},"ColorCode"],toColor("black"))

Thanks! Sometimes obvious workarounds can be difficult to see.