I also have not encountered a similar task before, so it became interesting for me to implement animation in WPF. This may come in handy somewhere in the future for other tasks.
By the way, during testing, I found that animation freezes occur only when the splash screen is launched before loading the main script in 3ds max 2021. If you run in 3ds max 2020, then there are no freezes and the splash screen works smoothly and stably. What is the reason for this, I still cannot understand.