Write/Read command on Characteristic doesn't work on Android

[Krodz]

Hello !

I have this device I need to read data from but the constructor created a custom service.
In order to get informations like DeviceID I need to write a command on a characteristic and read the result from another one.

The two characteristics have the same GUID, the differences are the rights (one can only write, the other can read/update).

While I write my command on the WriteOnly, the event "ValueUpdated" of the other characteristic is triggered but the characteristic value is always null.

var characts = service.Characteristics.Where(c => c.ID == new Guid("81eb77bd-89b8-4494-8a09-7f83d986ddc7"));
writeCharact = characts.FirstOrDefault(c => c.CanWrite && !c.CanRead);
readCharact = characts.FirstOrDefault(c => c.CanRead && c.CanUpdate);
if (writeCharact != null)
{
var cmd = ToMeter("&W "); // Just my command it will send "&W 58287"
readCharact.ValueUpdated += async (sender, e) =>
{
var readValue = readCharact.Value;
var c = await readCharact.ReadAsync();
var id = c.Value;
};
readCharact.StartUpdates();
writeCharact.Write(cmd);
}

This code works on iOS but doesn't on android. I can scan the devices, discover the services, discover the characteristics with no problem. Only this scenario doesn't work.

Any ideas?