Its been like that for quite some time (> 1 year) and no fix seems to be in sight.
There a lengthy thread on the topic. https://www.waze.com/forum/viewtopic.php?f=56&t=124948
The below has been used around the harbour and in the Northern Beaches area as a work around for now… not ideal but it works…
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Thanks and fair enough… back to the question then - is there access to the water layer of the map to correct these issues? I see stevethompson49 has asked regarding removal so will be interesting to see the response?
OK… I cant see that place from my lowly rank of 2 
No probs. No doubt they will fix it sometime.
Yes. Only has Venues, Residential, and Parking Lots listed as selectable options. Sound right?
Ah OK - right I can see that - but you are saying that changes have no effect at the moment?
Brilliant…
Try making an edit to a segment to force a tile update.
Further note to this… the sea that ituajr is updating is only from Palm Beach to Shellharbour. North of Palm beach there is no such “sea” until Copacaban NSW.
yet on the app there is water shown - so there must be another map layer showing the water on the app that we cannot see to edit?
So begs the question… how can this be fixed?
I guess thats my point - on the app there is a sea off Copocabana. ie that there is another underlying layer on the map that we cannot see or edit. its not shown on the editor, but does appear on the app.
agree - can only keep bringing it to the attention of the developers that there is an issue in that we cant correct this underlying sea layer