Using Heatmap plugin with Shopify

Hey, we use Matomo on our own hardware and have started to evaluate Heatmap plugin.

This is our config:
Matomo version: 5.3.1
MySQL version: 11.7.2-MariaDB-ubu2404
PHP version: 8.3.19

We have started to add Matomo to our Wordpress website. That works as expected. We see the default Matomo statistics and also Heatmaps.

Then we started to add Matomo to our Shopify shop. We have followed the documentation.

We get also the standard Matomo stats. But we get no heatmaps. I checked that we have reached at least 1000 page views and I have set the sampling rate to 100%.

I think my target page rules are fine.
I would love to have a check function that could be used to check which of my current pages are matching my current target page rules.

What could may be going wrong on our side?

This is our Wordpress website:
trackle dot de
This is our Shop:
shop dot trackle dot de

Thanks.