paulus1031 Update: Have tried further workaround and tweaking.
This might derive the purpose sought for :
1) Try add this to custom.css file (As Paul suggested, Kindly disable specific plugin during development phase)
@media (min-width: 320px) and (max-width: 480px) {.ja-topbar .stickymenu{position: fixed !important;top: 0px;
z-index: 999;float: none;width: 100%;display:block !important;background:#fff;} }
.ja-topbar .stickymenu.affix{position: relative;}
2) Upload and replace the specific file (Do ensure to take backup of current file in case if restoration needed)
/templates/ja_focus/tpls/blocks/header.php file
Note: Kindly presume this to be experimental customizations and do test/verify rigorously for the same in varied ways