Since upgrading to 3.13 all of the sessions where a user id was set get a new visit created for each action.
I'm using the piwik_java_tracker and looking at the code it puts a new random string the the visitor id of each request. This has worked fine in the past, both when a user id was set and when one was not set.
Probably related to https://github.com/matomo-org/matomo/issues/15205
@tolomaus by the sounds the piwik_java_tracker does not set a visitorId (
_id url parameter). Could you create an issue about this in the java tracker issue tracker https://github.com/matomo-org/piwik-java-tracker/issues
Sure will do, thx