Helix Ultimate 2.0.6 - Wrong output Phoca Cart Product-View-Items?

Dear friends,
just installed Joomla 3.10.5 with Phoca Cart and Helix Ultimate 2.0.6
In the shop-product-view the content of the tabs (at the bottom) are not displayed by surfing the page!
Sometimes, switching the tabs, the content appears in the tabs. By making a refresh of the page no content is displayed again until you switch the tabs!
I tried with other templates, there all is shown normal!
Here is a picture of the problem: http://shop.keltics.de/images/temp/Template_Fehler02.jpg
Just take a look at the live-site, please:
For your testing, I made a 1:1 copy (same server, same content etc.). The original runs with helix ultimate you find here (just see the product-view, f.e.:)
Helix Template
https://shop.keltics.de/shop/sortiment/18-cd09
Phoca Fashion Template
https://test.keltics.de/shop/sortiment/18-cd09
Just scroll down and cklick on "Beschreibung" or "Ähnliche Produkte"
Refresh the site - empty again?!
What is wrong? What we could change?
Thanks for a info, best wishes
Reiner