Steps to reproduce:

1. Update NVDA to the latest "next" snapshot (next-15324,255cb03f).
2. Try to switch between input languages with Alt+Shift. My input languages are 2: English U.S. and Bulgarian Bulgaria.

Expected behavior:

NVDA should report the input language change.

Actual behavior:

NVDA only plays its error sound.

System configuration:

• Operating system: Windows 10 Pro version 1803 (build 17134.112), 64-bit, in Bulgarian with all locale settings set to "Bulgarian".
• NVDA version: next-15324,255cb03f.
• Processor: Intel Core i5-4670 at 3.40GHz.
• RAM Memory: 8.00GB.
• Graphics: MSI GeForce GTX-1050TI Gaming X 4G, 4096MB dedicated memory + 4065MB shared system memory, desktop resolution set to 1920x1080.
• Sound Card: Realtek ALC887 at Intel Lynx Point PCH - High Definition Audio Controller.

Other questions:

I'm attaching the NVDA log with the logging level set to "Debug".
NVDA_Log_2018-06-19.log