Blocks built the same but explode different

Can anyone tell me the difference between the two blocks in the attached file please?

When I explode the 1 on the left, it changes the outline of the tree to a polyline - this is the desired effect I want!

However, do it to the tree on the right and it explodes the line to many little lines! - NOT what i want!

I've looked at them both in block editor and they both seem to be constructed with poly lines so I thought they should both explode the same?

Can anyone tell me why they dont?

Thanks everyone

Trees.dwg

Not sure why, but if you change both of the blocks insertion scales to a value of 1, then explode them both; they both retain the polyline

ah, wish i could do that! ive had to scale them all serparatly (in my main drawing I have roughly 160 trees shown) to show their verying size! i need them all to be polylines to be able to trim them around eachother!

The troublesome one has different scales along the X & Y axes.

It seems that if the scale is set equally, the polyline will be retained.

hmm thats what it looks like! although im afraid i cant scale them evenly for what im doing!