Force Elite Cataphract to use shields during sieges

Before starting a siege, be sure to divide your infantry and archers into two groups.You don't have to do this, but then the AI will automatically storm the castle without your order.

Put these two units as close to each other as possible. And give EVERYONE press "0" the order to form a linepress "F9".

Press the "ready" button then wait about 2 seconds and give the order to build the wall of shields press "F8".

I also recorded a video where I use this method from the beginning to the end:
https://youtu.be/SZalAqpzRx8

Even following these instructions, 3 times out of 10 I was able to make a wall of shields.
Considering my army is made up of 50% Imperial Elite Cataphracts, this directly affects the game. So I spent a few days looking for a solution to this problem..

So write in the comments whether my guide was able to help you and how you were able to solve this bug. Or am I the only one so lucky that I decided to use the most buggy unit in the game...
Interested to read your experience with this problem.