Image Hotspots, hotspot/s not visible in Firefox but visible in Chrome

UPDATE: Resolved. After a work colleague found it was working in Firefox on his machine, I investigated further. Still not sure 'what' the issue was, but clearing Cookies and site data worked.
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Effectively after creation of an H5P Image Hotspot content. This works with no issues when viewed in Chrome but the hotspot marker is not visible (and no interactive area if you hover the mouse over the space the marker should be in) in Firefox.

Platform Moodle (V3.x)

Desktop

Chrome - Works
Firefox - Not working

H5P plugin version : ??

H5P content type: Image Hotspot