Can someone please help me on this? I am getting lot of userId and device info types as unspecified.Tracking is also working fine so I'm wondering from where does it comes from? Also whether giving the Expire After event as visit will make this issue?. Attaching the screenshot for reference.
Track Device Info seems to be a custom dimension? How is this being populated?
User Id is also a custom dimension...
Without knowing about your tagging, when things are being set, how they are being set it could be hard for us to help..
That said here are some general thoughts:
If you are using code to populate those dimensions, is there a chance the code is failing sporadically? Is it possible that the code to run the detection could still be happening in the background, letting the tracking fire before the information has been retrieved?
Are you only setting on the Page View and allowing the Visit level attribution to set the actions? Is it possible that sometimes the first call on the site is an action and not a page view, and therefore no value has been set yet to "carry forward"?
Do you have other platforms (mobile app, amp, subdomains, etc) being captured in the same suite? Are all of those platforms setting the data correctly? (Note that on Mobile App Lifecycles, this is the first call when an app is opened, and generally it's missing all the context variables so this can be a big area that creates a lot of unspecifieds)
What is your User Id? Is it the Adobe MID tracked in an eVar so you can see it from Workspaces? Is it a system level "logged in user" id? Any pages prior to logging in would result in no value if this is a system value.
Have you tried to run an correlations in Workspace to try and find where the data is coming back Unspecified? Is it on certain pages? Certain Actions? Is it from a different platform? Is it possibly the first hits on the site, then subsequent hits have the data?
How in-depth have you tested your implementation? Have you been able to replicate your eVar being sent without a value (and still not having a value in the post-processed data)?