Cannot set a terraforming zone on edge of map

Issue description

(Edit: please read my comments below; I may have my interpretation of what's happening backward)

Hey, folks, Along one edge of the Armageddon map (started during update 3), I cannot zone along one edge of the map. I tried uploading a file, but keeps saying it has failed to load the save. A stacker can dump along that edge, and the control towers can outline the space all the way to the world edge.

Reproduction steps

Seems to be reproduceable with no prerequisite steps. Just try to set a terraform zone on one edge of the Armeggedon map from Update 3 (edit...this was started in update 2, not 3, which is why there are no trains). I used to be able to mark this (as demonstrated by other older zones that were extended to the edge).

I believe it's the edge that the easy start would be closest to.

Game version and build number

v0.8.2a b552

Operating system

Windows

Attachments

If the save file is too large, attach a link to some cloud storage, but don't forget to share the file in the cloud.

So, I may have this backwards after looking over it today. I noticed the problem yesterday when I see that my stacker tower has overshot the dumping zone that I thought extended to the edge of the map:

Well, maybe after all, the dumping zone is extended to the true edge of the map, but the designation area from the Mind Control Tower has overshot. The stacker tower has also dumped out 4 more tiles than it should have. This photo is the corner of the map, so you can see both map "edges" in this photo above. The lower white line cannot be placed any further, and the dumping zone extends fully to the edge.

In this next photo, this area shown was previously extended to the edge of the map before Update 4 dropped (by using dumping zones that extended to the map edge)....and now, while setting the area for the MCT, I can designate the area out 4 extra tiles (the size of one dumping zone square), but I can't designate a dumping zone on these 4 tiles with the terraforming tools. I would assume from the first picture that I can use the Stacker tower out an extra 4 tiles as well.

I did additional testing on all 4 sides of the map, and 2 sides are affected, not just this one. The other 2 sides behave as expected, and I have run stacker towers along both of those edges and they haven't over-extended their intended reach.

You see the "Invalid Position" because I'm trying to place a dumping zone between the ones that are already showing and the white line of the MCT. I don't get this "Invalid Position" on the other 2 sides in the same manner.

I can also build in this area where I'm getting the Invalid position, but I cannot build past the white lines of the MCT, as shown below:

Finally, here is the link to the save file in Google Drive.
https://drive.google.com/file/d/1uRE-kLfRuVFSsUsk1qloUplULQVm_3vw/view?usp=sharing

No mods have been used on this map...and was started roughly 1-2 months after Update 2 dropped. I also didn't do much on this map during the period following update 3, as I played on Dragon Tails to experience the trains, but came back to this map in the weeks after the Update 4 release date announcement.

I ran into a similar issue on Shattered Isles. My Stacker tiles overpoured to the edge and now I can't dig out all the way to the edge to fix it.

No mods, just vanilla.

Save:
https://drive.google.com/file/d/1sqg8kWkqJamTrCD2f6E6ldDz-i6MqxbE/view?usp=drive_link