Landscape Painting Issue

I painted several varieties of shrubs and trees with a ground material to an entire level. I noticed a few trees that were a little too close to a path I painted earlier so I decided to remove them. Returning to the Foliage tab I chose the pointer and then the tree, it wasn’t selected. I attempted to do the same with the lasso tool with the same result, not selected. I did notice whichever tool was used, instead of selected an object or group of objects the engine instead selected(highlighted, outlined) the entire level. I’ve revered the level back to a state prior to the landscape painting before waiting a day to paint again. I had the same end result.

I ensured each time that the level I was painting on was the current level.

I’m at a loss to understand why this is happening. Can anyone provide a pointer or two on how to remedy this, preferably without having to start over again, so I can avoid this in the future?

Thanks in advance