Deactivate dual SIM?

I have a Huawei mobile phone with a dual SIM slot and use one SIM for private use and the other as a work SIM. When I deactivate my work SIM (under Settings -> Mobile network → SIM management) my mobile phone no longer recognizes various numbers as if they were not saved. However, I had already saved these numbers on my private SIM before I received my work SIM. I have not saved these numbers on the work SIM.

To my question:

1. What's wrong here?

2. How can I deactivate my work SIM without losing my home SIM numbers?

Until now, I always had to completely remove my work SIM from the phone in order to be able to keep my numbers. However, this is very impractical…

Save the numbers in the mobile phone and not just on the SIM card, then it should always be recognized.

Thank you for your help. Unfortunately then the problem is not solved. In the sense that I don't understand why it is. It also makes it difficult for me to take the number with me if I want to change my SIM in the future.