Hi vincent.tirtiat,
Please post questions in the Q&A forum. In addition, direct related questions to a specific tutorial can be asked by pressing the Help button under the tutorial.
Thanks for considering it. Otherwise, the forum becomes hardly readable. Hence why I have moved your post.
Please share the file. I can’t see the elbow controller, so it is hard to reproduce. Thank you for your effort; I appreciate your idea of making it easy for me. Images often contain only a minimal amount of information compared to a scene file.
(If you share an external file: I click only on primary cloud services: Dropbox, Amazon, Wetransfer, Apple, Adobe, for security reasons, I share too many files to take risks). If you need an upload link, as the attachment system here requires zip and is very picky with that [yes, all about security], let me know, I’m happy to set a temp URL up)
Have you tried to move the Pole? That seems to be the problem here; I can’t reproduce it in any other way. But well, questions always feel like a waste of time, compared to a scene file 
So, here is one, and please have a look if that works for you.
https://www.amazon.com/clouddrive/share/ygog1FIxxZwLQyYJIXXXVB7f3tvZoFsMKnglAiursaR
Cheers
More about that subject, if that was the problem:
https://help.maxon.net/c4d/s24/en-us/Default.htm#html/TCAIK-ID_TAGPROPERTIES.html?TocPath=Object Manager|Tags Menu|Various Tags|IK|_____2