Both versions are (roughly) synonymous and both should work and do for me in my tests.
@ridgerunnersjw, what device OS version are you targeting?
I'm pretty sure Workbench uses C++14 for Device OS 1.2.1 and later.
Maybe you should test such hypotheses in a stripped down test project to exclude any other factors that may contribute and which you can share in its entirety too.
As commented in this thread