Make sure you have CTCSS setup correctly on your FT1500 to match your HT settings.
Select "V" in simpleusb-tune-menu (Item 12 of the Admin menu) to verify you have COS set correctly.? Make sure CTCSSFROM Mode is "no" ( "L"? in simpleusb-tune-menu)
Select "2" in simpleusb-tune-menu to check/adjust RX voice level.