Hello erreart
Sorry we could not respond sooner. It looks like you are no longer using Landing Page cat, so I will mark this as resolved.
Landing Page Cat should be fully functional on all mobile devices. If it is not, it will be due to interference from another plugin or the theme. For us to work on this issue we would need you to isolate the conflict.
To search for conflicts, please follow these steps.
1. First please deactivate all plugins except Landing Page Cat and see if the issue persists.
2. If the issue is resolved, reactivate your plugins one by one, testing after each to see if the issue returns.
3. If no conflict is found among your plugins, try reverting to a default WP theme like ‘Twenty Sixteen’, or ‘Twenty Seventeen’, and see if the issue is resolved.
Head here for detailed instructions:
https://fatcatapps.com/knowledge-base/search-for-conflicts/
Get back to us with your results, and we will go from there.