Hadn’t noticed this before, but I was messing with my computer so I put Zwift on and was watching from helicopter/blimp view. The lagoon with the little land bridge right after the finish line has several boats in it, but no ocean access! How did the boats get in there and how do they get out? The lagoon is too small to go boating in so we need a bridge with ocean access. 
At high tide the boats can get in and out of the bay. As for why you’ve not seen these high tides, it’s probably due to global cooling due to everybody in the Zwift World riding bikes rather than driving cars, causing the ice caps to be restored, reducing ocean levels and thus trapping the boats.
Anyway, it’s just a theory; we’d have to hire a scientist to really sort out these details, so for now I’d say just enjoy the view.