There are a number of posts citing problems with the keyboard not being connected, not working, with the Ultra S10 (and others).
There are many unhelpful solution suggestions.
What works is to be sure the cover is properly connected to the screen. Even if it is slightly offset, the keyboard may not work. So, it's not the 3 pins on the bottom. It is good alignment of the top of the cover with the top of the screen. (So far, that's worked everytime, for me.)
Thanks for sharing this solution! I’ve come across the same issue with the keyboard not connecting, and it’s so frustrating when the usual fixes don’t seem to work. I tried aligning the top of the cover with the screen like you mentioned, and it made a difference! It’s crazy how something so small can be the root cause of the problem. Glad to know it’s worked consistently for you too. Hopefully, this helps others who are dealing with the same issue. Appreciate the tip!
I'll add my 2 cents. My S9 FE+ would not connect with the slim keyboard. There was no error. I returned the keyboard and received a replacement- it still didn't work. I came upon a solution on Reddit to install ONEUI 6.1.1. That solved the problem. WHY would Samsung not push this update to new tablets automatically? I had to hunt to find the update. The keyboard worked seamlessly after. Samsung is going to get a lot of keyboard covers returned over this.
