Spacial Awareness & Form Manipulation Advice

Hi, i am new to line of Action, I don't know if its forbidden to ask feed back on exercises from another platform, if so i will remove this post immediately, but i would like to ask for some advice on form manipulation. I started to learn perspective about 3 weeks ago and after a lot of practice i managed to get the hang of it but ii came across a problem while trying to manipulate form in space.
Do you have any exercises that could help me develop this particular skill?
The exercise is in the link below, i copied the link from my original post from Artwod and i think anybody can give feedback  even without a subscription.
Thank you for taking the time to help me.

Artwod Exercise

I clicked the link but It said the feedback request had expired.

Thank you for taking the time to help me.
I have figure out what was the problem that was blocking me in the volumetric drawing.
I appreciate a lot the help.

The link expired because i realized that i could figure out the problem on my own if i pushed hard enough.
I am sorry for the making you was time trying to help me.

dont worry, it happens.