There is a mountain just to the west of my capital. Naturally, I want to place a campus district next to said mountain to gain the adjacency bonus. Only I can't, the game won't let me place it in any tiles adjacent to the mountain and it gives no explanation as to why. Here is a screenshot.
As you can see, I own two tiles adjacent to the mountain. The tiles aren't on farther from the city center on the left than the legal ones on the right, and I can freely work the tiles. I checked the Civilopedia but cannot find any additional restrictions. So what gives?
Any know what is going on. I would greatly appreciate the help.
Thanks.

As you can see, I own two tiles adjacent to the mountain. The tiles aren't on farther from the city center on the left than the legal ones on the right, and I can freely work the tiles. I checked the Civilopedia but cannot find any additional restrictions. So what gives?
Any know what is going on. I would greatly appreciate the help.
Thanks.