Hey Heike,
first of all, thank you for the purchase!
I was rather perplexed when I couldn’t replicate the bug on a fresh Sensei install, yet then realized that its cause is in the translated string, or, rather, in my myopic code :) the filter script used the textual contents of each filter button to tell if it was an “All” option or any other tag, which wasn’t a translation-proof approach (since the translated text is “Alle”, the script did not recognize it as a filter-reset button). I’ve prepared a fix, please download this archive, unzip it, and upload the contained files into the theme directory (i.e. /wp-content/themes/Sensei/), then download this archive, unzip it, and upload its contents into the following directory: /wp-content/themes/Sensei/scripts/filterable-portfolio/, replacing the existing file as well. Please let me know if the fix corrects the bug!
Sincerely,
Andrii / Satori Studio