Hello there!
We have set up ruby APM integration with a Rails application, and we are having an issue that I can't find why it's happening.
Kibana version: 7.3.0
Elasticsearch version: 7.3.0
APM Server version: 7.3.0
APM Agent language and version: apm-agent-ruby gem 3.7.0, ruby 2.4.3
Description of the problem including expected versus actual behavior. Please include screenshots (if relevant):
When we access de APM UI for visualizing the transactions, all graphs work okay, except for the transaction timeline (waterfall).
We expect to see the spans inside the transaction like this, so we can see the time spent in each span (the image was taken from the documentation):
But for all the transactions we see the waterfall like this:
The indexes from APM (apm-*-transaction and apm-*-span) are populated correctly, and we have spans associated with the transaction/trace id.
We don't have any additional configuration or custom instrumentation.
Also it seems strange is that we have the following "Time spent by span type" chart populated but not the transaction waterfall:
Provide logs and/or server output (if relevant):
I took one example from the apm indexes:
If you have any hint of what might be happening here, any help is welcome!
Thanks in advance! 
