@eric007
I have the same problem. It is related to Domoticz update sice today afternoon where some of the sensors started to show like undefined. This has nothing to do with Mysensors 2.3.0 update.

@eric007
The problem is in browser's cache was not refreshed after the update. For Firefox browser clear Cache and Site Data (Options->Privacy&Security->Clear History->Cache+Offline WebSite Data)
then reload window. The message "refreshing cache" should appear on Domoticz page, right up side corner.
The graphs should then display normally. Without clearing the cache you can see the normal Domoticz graphs in new private Firefox window or other browser.