Yes, formatBeforePublish is visible as Outgoing Value Format in UI.
And the screen and description you have posted from version 2.5.12 above is the same as in version 3.1.
Unless you have changed some part of the code for Wemos (apart from obvious like password etc of course) it should work.
You can check as follows:
0. Not sure if you have bought or built your converter. If it was built ensure Tx/Rx are connected in the proper way.
- Do your items have %s as well in their definition?
Switch CA_MuteState "Mute [%s]" <soundvolume_mute>(gAzure) ["Switch","SoundVolume"] {channel="mqtt:topic:cambridge_audio:mute_state"}
- I would check if the syntax ‘{“mute” : “%s”}’ from version 3.1 works in version 2.5.12 as well?
Seems there were some issues, see the the bottom of [SOLVED] Update item state from MQTT string - #14 by Zugarelli
Make sure to restart Openhab or clear cache
Try with different syntax like {“mute” : “%s”} without single quotes
- If it does not work and the openhab setting seems OK you can check if the mqtt message is delivered to Wemos. You will need to debug in Wemos and in order to do it you need to switch to serial monitor or add ESP8266WebServer.h library to present the staus/display of the selected message (ex mute)
PS. I have decided to migrate to version 3.1 and despite number of bindings and DSL rules I have got it was painless:-). In my case the 3.1 running o RPI3 is more stable than 2.5.12 