Another general - most annoying issue while entering e.g. categories

Click on "Add new category" (e.g. posts, people... or any other feature with option to enter/add categories) then enter name of category.
Next entry of name fiel does not disapper anymore nor popsup slug entry... submit button seems not to work proberly/shows no reaction.
BUT
if I refresh the category page e.g. by choosing the 'list all' categories the entered text appears in the list of categories/correct orderd (in the CATEGORIES PAGE).

Research for a solution in WP forum; recommendation to check the functions.php file and/or deinstall theme plus child theme... did all that. No error in functions.php file nor any change of given problem.

// PLUGIN SIDEBARS
if (function_exists('register_sidebar') && class_exists('Woocommerce')) {
register_sidebar(array(
'id' => "canon_woocommerce_widget_area",
'name' => 'WooCommerce Widget Area',
'before_widget' => '<div id="%1$s" class="widget %2$s">',
'after_widget' => '</div><hr class="dots"/>',
'before_title' => '<h3 class="widget-title">',
'after_title' => '</h3>'
));
}

if (function_exists('register_sidebar') && function_exists('bp_is_active')) {
register_sidebar(array(
'id' => "canon_buddypress_widget_area",
'name' => 'BuddyPress Widget Area',
'before_widget' => '<div id="%1$s" class="widget %2$s">',
'after_widget' => '</div><hr class="dots"/>',
'before_title' => '<h3 class="widget-title">',
'after_title' => '</h3>'
));
}

if (function_exists('register_sidebar') && class_exists('bbPress')) {
register_sidebar(array(
'id' => "canon_bbpress_widget_area",
'name' => 'bbPress Widget Area',
'before_widget' => '<div id="%1$s" class="widget %2$s">',
'after_widget' => '</div><hr class="dots"/>',
'before_title' => '<h3 class="widget-title">',
'after_title' => '</h3>'
));
}

if (function_exists('register_sidebar') && class_exists('TribeEvents')) {
register_sidebar(array(
'id' => "canon_events_widget_area",
'name' => 'Events Widget Area',
'before_widget' => '<div id="%1$s" class="widget %2$s">',
'after_widget' => '</div><hr class="dots"/>',
'before_title' => '<h3 class="widget-title">',
'after_title' => '</h3>'
));
}

/**************************************

Next delete cache... de-/reinstalled wp-superchace plugin.

Result: The issue not having a refresh of entry page after entering needed category... entry is visible only after listing all categories.

Please: Any other possibility to solve the problem? Have to enter heaps of shop categories...

Many thanks in advance for additional helpful advise.
Prinz