Filtering Issue - GA4 & Looker data are different for the same filter

[Ben06]

Hi,

I have a filtering issue in Looker with GA4. I am trying to display my traffic by Source / Medium in order to show all the traffic coming from Search Engine Marketing channels.

Data in GA4

In the past 28 days, GA4 shows that I had 655 sessions coming from:

• google / cpc,
• bing / cpc
• adwords / ppc

Data in Looker

When I apply the same filter in Looker, I see only 80 sessions.

I do not undersand why for the same set of data, the same filtering, the results are completely different. 

Please note that when no filtering is applied in Looker, the data matches exactly those of GA4.

Thank you in advance for your help.

[data_trevor]

I am having a similar issue. Anyone able to offer a solution?

I am looking at total user numbers for September and October and running breakdowns by Channel Grouping and Medium. Looker Studio agrees with GA4 in total traffic numbers for both months. But when I run a breakdown by Channel Grouping or Medium in Looker Studio, the October numbers are WAY off from what GA4 shows, and seem way off from reality as well.

                                                                 September                  October

GA4 Total Users                                     1441                            1324

Looker Total Users                                1454                            1339

GA4 Organic Search Users                  494                              447

Looker Organic Search Users             518                              108

That 108 is clearly suspicious, but what is going on? Can anyone help?