SmallHD FOCUS audio meter problem

I have been trying a SmallHD FOCUS on my GH5 which I really like as an external monitor but have encountered a problem with the audio level meter in the FOCUS. Basically, it reads 6dB too low compared to the camera meter and to the levels displayed in Premiere Pro. I tried a second FOCUS with the same result. I then tried my two other cameras – a Panasonic G80 and a Sony A77ii with identical results. There seems no way to adjust the audio levels in the monitor and I have gone through all the camera HDMI settings. I record in 4K, 10bit, 25p. on the GH5. I have contacted SmallHD but they have not been able to suggest a solution. I would be really grateful if anyone with a FOCUS would be able to check if their audio meter is doing the same thing or giving the correct reading. I suffer from hearing problems and consequently find difficulty in using headphones relying more on the meters. Many thanks,