S23 Ultra S pen can't touch a spot

[Reep]

I recently have a S23 ultra and while using it, I noticed that there was a spot that the S pen couldn't seem to work on the screen. Hence I tested it by trying to color the screen and the photo below shows the outcome. 

Coloured page to indicate area with problem

I noticed that no matter how hard I pressed the S Pen on that part of the screen, it somehow doesn't respond. With that going on, I couldn't select the smart select option in the S Pen menu as shown below:

But on the other hand when i use a finger to tap on that part of the screen, the screen responds to it. Does anyone else face this issue too and does anyone have an idea on what may be the cause of this? 

Side note: I used another seperate spen to test and the outcome is the same as this

[davychoo]

Remove your phone case and try again, some magnetic part in phone case will affect Spen to function properly

[Reep]

It worked, thank you for your advice :)

[davychoo]

Welcome, I remove the magnet in my phone case and the problem solved.

[theroytravels]

Try removing any third party cases and restart your device. If it still doesn't work, contact customer service to check on the hardware.

[Reep]

Yup it worked, thanks :)

The problem was from the magnetic part of the phone case

[KampungBoyFormula]

1) Remove all phone cases & run Phone Diagnostic to see if it detects any issues, esp on S Pen & Display.

2) If it's hardware, send in to Samsung Centre to check & claim the warranty.

Had encountered something similar on Z Fold. Using hand is ok, but using S Pen can't touch on certain particular area only. Samsung Centre changed the entire display. And while there had changed to a new battery as well.

[Reep]

Noticed it was the phone case causing it, thanks for your advices too :)

[KampungBoyFormula]

Had the same issue on my Note phone once likely due to 3rd party case magnet.

[scinex]

It seems more towards display issue. Better to visit SC at earliest since it's still under warranty.
All the best.