Tellstick and a Nexa LMLR-710 doorbell

I have registered a doorbell (Nexa LMLR-710) as a switch in the Tellstick software. It works fine to use the Tellstick software to turn it on; it chimes beautifully. The state also shows up in OH as expected.

The item is configured like this;

Switch SW_Bell “Bell” { tellstick=“8:Command” }

When I try to send a command through MQTT it responds:
“Cannot send ON to null”

I then try to send the same command to MQTT to another device I have configured - a Nexa plug-switch configured like this;

Switch SW_Switch “Switch” {tellstick=“3:Command”}

It works as it should, happily switching the device on and off.

There must be some logic in the plugin not seeing this switch as a “settable” switch for some reason… Strange thing. Anyone?