Grafana charts timing out

I’m running OH on Ubuntu 17.10 on amd64. I’ve recently set up InfluxDB with OH, and also hooked up Grafana to them. All of these run on the same box. I have added charts from Grafana to my sitemap.

I’ve noticed that if I open Habdroid, Grafana charts are displayed just fine. However, if I visit the Basic UI, I don’t see the charts, and if I run Habdroid afterwards, charts don’t appear there either. Also, when charts fail to load, I get “Proxy servlet failed to stream content due to a timeout” messages in the log. When this happens, the images can still be downloaded from Grafana using wget, from the server itself, so Grafana is still functional. Also, I think it’s highly unlikely that requests to Grafana would time out, since it still generates the chart images in 2-3 seconds, just like before. The only way to resolve this issue is to restart OpenHAB, and not have the Basic UI try to load the charts.
I have also noticed that if I add a random image from the internet to my sitemap, that loads both on the Basic UI, and in Habdroid, even if Grafana charts don’t load anymore.
I have been able to reproduce this issue consistently anytime.

Any idea why opening the Basic UI messes up the charts?