Undefined value in fallout report

[spy237]

While adding a pagename in fallout report, I am seeing 'undefined' value in one of the steps. Can anyone explain why this is coming? Screenshots for reference

[prads]

If a visitor remains unknown to the stitching service (there are hits coming from a device that could not be attributed to a specific person)

[fhusain]

We have a open bug for this issue where in some case, we are seeing undefined visits in the fallout. So it could be related. We are expecting this one to be fixed by this month.