Localization broken in APS Testing

I posted this bug before directly in the APS thread, it was promptly fixed, but has cropped back up.

Every time Translator:FormatByKey() is called, the following error occurs:

Key “ExampleKey” for locale “” not found in any active LocalizationTable

where ExampleKey is whatever the key was that was passed to FormatByKey.

The error is specific to the following usage:

local translator = LocalizationService:GetTranslator(LocalPlayer)
local text = translator:FormatByKey(key, args)

The error does not, however, occur when I set up the translator in this way:

local translator = LocalizationTable:GetTranslator('en-us')

From the error message, it appears that Studio thinks my LocaleId is an empty string. The LocaleId still shows up in LocalizationService as en-us for both SystemLocaleId and RobloxLocaleId .