Since I have updated Wordpress to version 5.6 the slider in Sparkling theme isn’t working anymore but only one static image is displayed now. (This issue seems to be only occur in Firefox. In Chrome or on Android or iOS it strangely works).
I noticed that Wordpress 5.6 is using a newer jQuery-Version, so I assume that the issue is related to an incompatibility with your theme and jQuery 3.3.2 (which seems to be used now by Wordpress).
I tried to debug the issue and temporarily installed the plugin “Test jQuery Updates” and activated jQuery 1.12.4 and jQuery-Migarte.
JQMIGRATE: jQuery.fn.load() is deprecated
As far I understand (I am not a web developer) the issue seems to be in flexslider-custom.js.
Finally I removed “Test jQuery Updates” because as per its description “it is not intended for use in production environments”. So this workaround is not an option for me.
I would appreciate a workaround until an update for the theme is released (without installing additional plugins but perhaps you can provide an adapted version of flexslider-custom.js).
As far as I saw the latest update of Sparkling theme released on 18th October 2019. So I wonder if we can expect another update at all?