Unable to use guides when transform tool is active

I use  the guides to define where my slices should be. I used to use the transform tool (cmd T) to define the bounding box of my asset and then drag guides to the edge of the asset so i could see where it ends.

However with the new update (CC 2019) I can no longer drag guides while transform tool is active. So i have to guess where asset boundaries are and then keep moving the guides in between activating the bounding box of the asset.

This is highly inefficient.

So while i am super unhappy about this new development, does anyone know a way around it?

Here is my workflow:

The asset, it's unclear to see its boundaries without a bounding box.

I use transform tool (CMDT) to see the boundaries of the asset

Using guides to define boundary of asset
(this is the bit that has become a headache for me, how that i cannot drag guides onto canvas is transform tool is active. So now i have to do a lot of guess work in between activating cmd-t to see where the boundaries are. )

creating a slice guide box using guides as reference

Creating a slice using the slice guide