I'd like to add my notes here also.
Using Cura 3.0.3 and 3.0.4 I get the same issue. This is more obvious for issues when printing the first layer. When the gcode prints one support island then moves onto the next, there is no retraction and it leaves a string or globs of filament across the bed. This then also proves difficult to actually stick the first layer of each island as some of the pressure is lost during travel.
Retraction Minimum Travel is set to 0.8mm, the support islands are a good 30mm apart.
https://gyazo.com/94167280deee003c84b9e4fd3debd055
