(1) is not the least bit odd. However, I completely agree with you on (2).
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‘Highly odd’ 
Was riding London and the hills yesterday, noticed it, but something else too - the “you are here” indicator on the profile at the bottom of the map also stays at zero altitude. So as you climb up Leith, you are shown under the elevation profile, while the white dots representing other riders merrily follow the correct profile. What is peculiar about London is the elevation in that part of the map is “fake” - contrary to every other “real-world” worlds, the altitude in the London hills does not correspond to the ones in real life at those positions. Watopia does not count, they created the entire world from scratch (although it was located in a real set of lat-long coordinates).
So - the London graph is wrong, because it’s based on the wrong altitude variable. In all other locations, that’s not an issue, there is only one altitude value at each position. Only London has that situation. The correct variable with the correct data exists, otherwise you would be riding under the hills and there would be no slope. Do you have any idea how long it takes to correct such a bug? All you have to do is replace one of the arguments in the properties of the map object.
Also, at some point in the past this actually worked. So, it was broken in one of the updates along the way. I’m not sure how easy it would be to revert, but it doesn’t seem to be anywhere near the top of anyone’s priority list. But, you know, we got new foliage on the reverse Epic KOM with the last update. 
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New foliage?!? Awesome! Do you have a screenshot?
I was doing an over/under TR workout going up the reverse KOM this morning, and somewhat didn’t notice that foliage through the hypoxic haze. Go figure.
No screenshot, but what I noted was in the first approximately 1/2 to 3/4 of a mile above the new ‘KOM Bypass’ turnoff. Looked like some new bushes and trees, at least. I think I may have seen a few new pieces of foliage on the far side of the ‘force field’ headed toward the Jungle Loop, also.
This is probably how they introduced the bug in the first place.
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I agree, i think the London course must use two separate GPS plots and sticks them together, other worlds probably all use the same throughout the whole thing. so it is using the elevation from the main GPS bit when it is in the secondary GPS bit and so it just returns 0 for the whole thing.
I base this on no real knowledge other than a guess!
When debugging software, cases where an object (the map, elevation profile and gradient indicator) works in all situations but one, the first effort is to identify the difference between the one situation and the rest. And in this case, you indeed pointed out the one difference. The gradient indication works everywhere except the one place in one map where a different altitude map has been stitched in. It’s highly probable that this is the cause of the bug.
I’d agree with the assumption that it uses two separate GPS plots being the cause of the issue, except that the graph starts to go bad shortly after the main Start Banner, well before the tunnel warp to Surrey Hills.
As with most things that have gone wrong here in the UK recently, it is probably something to do with Brexit and/or the Government!
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Just to add a me too. I’ve a screenshot of this from around a year ago and have seen it consistently since then. Once upon a time it did work as expected.
About 5 weeks until this threads birthday, how should we celebrate?
Know issues - LOL
@Chris_Holton congrats. Zwift has finally got around to fixing this issue… by introducing the ability to hide the HUD. If it’s not visible it’s not a problem.
Way to go Zwift.
/s
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Zwift logic -
Some people want to save and not exit, no need to add anything let’s just stop allowing anyone to save and exit.
Some people want to customise the HUD, no need, let’s just remove it.
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Looks like we are going to get to this “known” issue’s birthday!
I know it shouldn’t but it really does annoy me, i find it hard to judge changes in gradient just by looking at the graphics so use the gradient in the map to help with gear selection.
That’s the idea with “known issues”. Since they are known, we don’t need to talk about them, and everyone including Zwift can ignore them.
So - it’s not a bug, it’s a feature.
Happy Birthday to this thread!
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Is anyone able to explain why this is so hard to fix? Or is it just not something Zwift want to fix or can be bothered to fix?
If it is never going to be fixed I’d rather just know so I don’t get disappointed with every update!
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