Why my website is not showing up when searched for in Google Maps pack in Google Search

I have a client and we’ve been doing SEO for them since more than the past 6 months now. We’re almost getting them on the first page for target keywords. It’s a local business and, thus, we’re doing Local SEO for them. However, the client is getting impatient. I’ve shown on Google Search Console that their website is showing up on page 1 for target keywords through the maps pack. I was able to achieve this level of reporting by UTM tagging the GMB website URL with:

Source: google Medium: organic Campaign: gmb-listing

This helped me pinpoint page 1 rankings. However, I’m finding it hard to explain to the client that you won’t see the listing all the time.

She searches and does not find the website. I’ve explained that today’s search results are personalised and there are several factors that affect the positions. I googled to look for an explanation of why it does show the impressions in GSC, but, may not show on Google all the time and to everyone.

My issue is that I can’t find resources online to explain to the client why you won’t see the Google Maps result when you search for it although impressions, page 1 (and position 1) ranking and clicks do show in GSC.