Maps work on single event page but not single location

I am seeing a strange inconsistency in my site where maps appear on one type of page but not another.

Single venue page where map does not fully work – balloon appears but not road map tiles. The zoom + and – icons are blurred.
http://www.corkentertainment.ie/venues/a-taste-of-west-cork/

Single event page where map works:
http://www.corkentertainment.ie/events/strict-2/

In the venue page I generate the map with code like:

global $post;
$location = em_get_location($post);
echo $location->output('#_LOCATIONMAP');

In the event page the code is very similar:

global $post;
$event = em_get_event($post);
echo $event->output('#_LOCATIONMAP');

The Chrome console only reports that sensor=false is no longer required for Google Maps.
Server error log is no help either.

I am open to debugging suggestions.

https://wordpress.org/plugins/events-manager/