@Klnvrsn2-0 as @chrishamm says, you are running out of RAM in that configuration. It's trying to allocate additional memory needed to queue movement for X and U at the same time, and failing because there is none available.
If you post your config.g file then we may be able to make suggestions about how to use less. Meanwhile here are some general suggestions:
If you use an attached 12864 display, keep each menu small and simple; Don't create a lot of tools; Don't use M595 to increase the movement queue length.