Problem appeared within the last 2 weeks, I did not notice it before then.
Mac Os High Sierra.
Muse's built in Composition Widget.
Website build method:
Responsive site built from scratch in Muse cc2018
Adaptive site consecutive upgrades from cc2014 to cc2018
Composition Widget set to display in Lightbox mode causes the Target to be centred horizontally between the top and bottom of the website instead of centred horizontally between the top and bottom of the browser - Widget has not been modified in anyway prior to unexpected behaviour - Widget did not display unexpected behaviour prior to approximate date stated above (Addendum) Lightbox view will display as expected in browser window after a time delay of about a minute (Addendum retracted) after further testing the initial problem remains
Composition Widget set to display Stacked with Vertical Transition prevents the trigger from being activated - known of problem since Muse cc2014
Composition Widget set to display Stacked with Horizontal Transition prevents the trigger from being activated - known of problem since Muse cc2014
Google Chrome - Version 65.0.3325.162 (Official Build) (64-bit)