Placing Zones in Cities Skylines

I’m trying to build a mod that places zones on a keypress. How would I accomplish this?

So far I’ve detected the keypress. But when I modify m_blocks in ZoneManager by calling block.setZone(x,y,zone) The block appears to have changed, but only for the moment. When I run the keycommand again, the data appears to have been reset. I never see the zone change in game, only when I print it to the console.

string outtext = "";
            uint blockCount = Singleton<ZoneManager>.instance.m_blocks.m_size;
            outtext += "start{n";
            for (int index = 0; index < blockCount; index++) {
                var block = Singleton<ZoneManager>.instance.m_blocks.m_buffer[index];
                if (block.m_valid != 0) {
                    block.SetZone(1, 1, ItemClass.Zone.Industrial);
                    block.RefreshZoning(0);
                    outtext += " valid:" + block.m_valid + " position:" + block.m_position.ToString() + " zone:" + block.GetZone(1, 1) + " n ";
                }
            }
            outtext += "}";
            Debug.Log("OUTTEXT " + outtext);

I’ve tried calling block.refreshZoning() as well, but I’m not sure how to calculate the blockid :(.

string outtext = "";
            uint blockCount = Singleton<ZoneManager>.instance.m_blocks.m_size;
            outtext += "start{n";
            for (int index = 0; index < blockCount; index++) {
                ref var block = ref Singleton<ZoneManager>.instance.m_blocks.m_buffer[index];
                if (block.m_valid != 0) {
                    block.SetZone(1, 1, ItemClass.Zone.Industrial);
                    block.RefreshZoning(0);
                    outtext += " valid:" + block.m_valid + " position:" + block.m_position.ToString() + " zone:" + block.GetZone(1, 1) + " n ";
                }
            }
            outtext += "}";
            Debug.Log("OUTTEXT " + outtext);