TileMap Unresponsive and Won't Paint Tiles


I have only been using PMNG for a week or 2 now so am not sure what I am doing wrong here.

I have created a TileMap, and linked a project. But when I try to add tiles to the project, the UI is very slow and it does not appear to painting the tiles properly. I am new, so I am not sure if this is me doing something wrong or an issue.

I had a look at this tutorial: Creating Tiles and Tile Maps with Pro Motion NG - YouTube

Again, I am not sure if this is something I am doing wrong, thanks for any help.