DateComponentsFormatter not honoring formattingContext

Question

When I use a standard NumberFormatter, it honors the formattingContext of .beginningOfSentence:

let formatter = NumberFormatter()
formatter.numberStyle = .spellOut
formatter.formattingContext = .beginningOfSentence
let string = formatter.string(for: 5)                 // "Five"; good

But when I try this with DateComponentsFormatter, it seems to ignore the formattingContext:

let formatter = DateComponentsFormatter()
formatter.unitsStyle = .spellOut
formatter.formattingContext = .beginningOfSentence
let string = formatter.string(from: 5 * 60)           // "five minutes"; bad, should be "Five minutes"

FWIW, I tried a variety of permutations, all to no avail:

• Tested different locales to make sure it was not just a bug in a particular locale (e.g., I tried both English and French, it localizes correctly, but does not capitalize correctly);

• Tested in macOS and various iOS versions (to make sure it was not unique to a particular platform/version);

• Tried changing the order in which I set unitsStyle and formattingContext;

• Tried explicitly setting allowedUnits and maximumUnitCount in case it was getting confused by the potentially variable number of units/components represented by the string; and

• Tried a variety of formattingContext options (not just .beginningOfSentence) and they all just return the same lowercased string.

I have worked-around the immediate problem by just applying my own sentence capitalization to the string. But I just want to ensure I am not missing something obvious before I file a bug report. Looks like DateComponentsFormatter simply does not honor formattingContext.