Here's an obscure one for the "broke it at 2.40" file.
When simulating your location by setting the 400t in Demo Mode, and then relocating yourself to a coastal ocean area (via the lower-right-corner tap from the satellite page), try executing a "Where To" -> Tides, select a tide-zone, and then tap the name (top bar) of the zone.
On two 400t that I have, they will both display the "High/Low", date/time, and tide height -- when running v2.30. Under v2.40, all I see is the column of "High" and "Low" text with no accompanying data.
Don't know what happens when you are actually AT the ocean, as opposed to simulating it, because, well, I'm pretty far away. But, this behavior is 100% repeatable on two 400t units when switching from 2.3 to 2.4.
Just sayin'
-Art