You've double-checked your tag implementation, everything seems to be working fine, but you're still seeing a (not set) landing page in your Google Analytics 4 (GA4) reports. If this sounds familiar, you're not alone. This (not set) designation can be a bit of a puzzle, but let's try to decode it.
Typically, (not set) landing pages in GA4 represent pages that were already open in a browser window when a user started engaging with your site. In these cases, a pageview event isn't fired because a page wasn't loaded, hence the (not set) designation.
However, these pages still register in GA4 if the user starts to engage with them. This engagement should trigger a session_start and a user_engagement event.
The (not set) issue can also occur when GA4 can't identify certain landing pages. These unidentified pages are grouped together under "Not set", which can sometimes account for a high percentage of your landing pages. This can limit your ability to analyze traffic and optimize high-converting landing pages.
So, how can you tackle this issue? The short answer is BigQuery.
You will need to create a custom landing page report using the GA4 BigQuery export. Don't know SQL? No worries, Simply utilize GA4SQL.com, a free tool that enables you to generate GA4 BigQuery queries without requiring any SQL expertise.
Also, if you're seeing blank landing page in your GA4 reports, please check: why is my landing page blank in GA4?
And, of course, we're all hoping that Google will address this limitation in the future to make the GA4 experience even smoother. Until then, these workarounds should help you navigate the (not set) landing page issue in GA4.