Extreme spawn changes from minimal setting changes

[DenFromEarth]

I have been trying to find a nice map today and I'm seeing some strange resource spawns as I make little changes with the slider bars for the frequency and size on the Resources tab. I'm using the Initial Scan mod (https://mods.factorio.com/mod/initial-scan) with the default 70 chunk radius to reveal the locations of the ore patches. I'm not using any overhaul mods or other mods that alter or add new types of resources to the game. These are some of the extreme changes I have seen which should not be related imo.

1) I found a map with a nice spread of copper and iron patches, and 5 separate oil patches within the 70 chunk radius. I started a new game with the same map string so I could increase the stone patch size from 25% to 33% which worked, but it also removed all 5 oil patches from the map which did not respawn anywhere else. The oil patches where not near any other resources and when I changed the stone setting back to 25% and restarted all 5 oil patches spawned back at the previous locations. I did not change any other settings.

2) I found a map with many iron patches and the only copper patch near the starting area within the 70 chunks. I increased the frequency of the copper resource in the settings by 50% on the same map string and the map regenerated with all of the iron patches replaced by copper and the only iron patch left was at the starting area. I did not change any other settings.

3) I had another seed with more coal patches than I wanted. I regenerated the seed with a 50% lower frequency on the coal and received a map with 6 uranium patches that replaced some stone and copper patches, but the coal patches were still there in the same locations that I had on the previous map string. All of them! Their frequency did not decrease! I did not change any other settings.

I have seen all of these many times today to a lesser extent with oil the most common resource to be changed or removed. I've used RSO for a long time and I don't recall such drastic changes to spawns after minimal differences within the map settings. So I have to ask, WTF is going on?