Still in Prologue as far as I can tell,
Dropped down to load the ballista.
Cocked it and enemies arrived. Handled that, then cock the ballista.
Ad Infinitum. is this bugged? Feel I am stuck in a loop. Must have repeated the process 20 times now.

When you say ad infinitum do you mean that you kept clicking the mouse to cock it but the action could not be completed?

No. I keep cocking it and more enemy come. Then I cock it again and the cycle repeats.
Can't get out of the sequence. Tho I did watch the youtube video and it seems to show an aiming sequence as well
Will try if that appears

1. LMB to cock the ballista.
2. Cut scene of soldiers approaching
3. Kill them
4. LMB to cock ballista
5. Jump to 2!

This is the prologue!!! WTF
I hope the rest of this game is better.

Sounds like you are not cocking it fast enough.
Are you getting it cocked before the bar fills?

And yes, the ridiculous QTE's are the worse part of the game.

I had no idea you needed to fill the bar! LMB and cock the ballista. LOL
Getting thru it now.
Thanks