Hello,
1. I have done some tests and I have the same error when I'm using OpenSDA. So, If you want to write into the memory by the debugger, you should use some advanced development tools.
2. When you run debug again the new application projet is loaded into MCU and the old one is erased. That is why the partition information is lost.
However, if you do not want to load new code into MCU you can use the "Attach" feature. This feature allows you to attach to the already running application. For example, you can check the registers. But if you want to load updated code (if you change something in your code) do not forget to change it back to the "Run on Reset" option.

I hope it helps.
Best regards,
Diana