Blizzard has pushed a hotfix to WoW Classic Era Realms addressing enemy pathing in water. This fix is already live for NA Realms and will be deployed to EU Realms later this evening.
Hi Metsa,
Thanks for the report. We’ve been working to untangle this issue for quite some time, and are happy to report that we successfully deployed a fix this morning for realms in the US region that were affected by this.