Adding MetaSlider Issue when adding Image

Under MetaSlider when adding a new slider or slideshow, then “add slide” this goes up in browser {“success”:true,”data”:{“message”:”The slideshow was successfully updated.”}}
with /wp-admin/admin-post.php being the call at the browser.
Some errors f12
HTML1300: Navigation occurred.
admin.php (1,1)
CSS3121: The media query -ms-viewport has been deprecated.
HTTP404: NOT FOUND – The server has not found anything matching the requested URI (Uniform Resource Identifier).
GET – http://——–/wp-content/plugins/1ml-slider/admin/assets/vendor/colorbox/colorbox.css?ver=3.11.1
HTTP404: NOT FOUND – The server has not found anything matching the requested URI (Uniform Resource Identifier).
GET – http://——–/wp-content/plugins/1ml-slider/admin/assets/css/notices.css?ver=3.11.1
HTTP404: NOT FOUND – The server has not found anything matching the requested URI (Uniform Resource Identifier).
GET – http://———/wp-content/plugins/1ml-slider/admin/assets/tether-shepherd/shepherd-theme-arrows.css?ver=3.11.1
HTTP404: NOT FOUND – The server has not found anything matching the requested URI (Uniform Resource Identifier).
GET – http://——–/wp-content/plugins/1ml-slider/admin/assets/css/icon-3-11-1.css?ver=3.11.1
HTTP404: NOT FOUND – The server has not found anything matching the requested URI (Uniform Resource Identifier).
GET – http://——–/wp-content/plugins/1ml-slider/admin/assets/tether/tether.min.js?ver=1
HTTP404: NOT FOUND – The server has not found anything matching the requested URI (Uniform Resource Identifier).
GET – http://——-/wp-content/plugins/1ml-slider/admin/assets/css/admin-3-11-1.css?ver=3.11.1
HTTP404: NOT FOUND – The server has not found anything matching the requested URI (Uniform Resource Identifier).
GET – http://——–/wp-content/plugins/1ml-slider/admin/assets/css/upgrade-3-11-1.css?ver=3.11.1
HTTP404: NOT FOUND – The server has not found anything matching the requested URI (Uniform Resource Identifier).
GET – http://——–/wp-content/plugins/1ml-slider/admin/assets/vendor/tipsy/tipsy.css?ver=3.11.1
JQMIGRATE: Migrate is installed, version 1.4.1
5 HTML1500: Tag cannot be self-closing. Use an explicit closing tag.
admin.php (276,806)
I just upgraded to WP5.1.1 and this was working in a previous version.
Thanks