And you are using the latest version of the Graphite module?
https://github.com/Icinga/icingaweb2-module-graphite/releases
To be honest, I’m mostly done with Graphite. The setup is fiddly with its many components.
This HowTo worked pretty well the last time I used it:
Or maybe check if you find a HowTo to run graphite in a docker container, that way you have it easier with the whole lot of components/dependencies.
Or you switch to InfluxDB and Grafana, which I am doing for all new setups.
It is pretty easy to set up (both InfluxDB2 and Grafana) and more powerful in regards to dashboards.