Retain variable not reliable

I use a few internal variables and they are set remanent. When I exit the runtime and start again the current value matches the value before the exit.
If I terminate the runtime e.g. via the task manager or the runtime is terminated when shutting down Windows, the variable has some value, but not the value before terminating the runtime.

Does anyone have a hint what I am doing wrong?

This is a migrated post! Originally posted on 21.04.2021 by user stefwe. Please be aware that information can be outdated.