What is this strange problem or issue?

[DarkRadiance1983]

I wrote a blueprint node in C++ to perform a lookup table function. Each time I compile it, the node works fine. However, whenever I close the UE4 blueprint editor and restart it, the node becomes non-functional. I have to keep UE open and recompile the C++ code for it to work again. What could be causing this issue?

After compiling just now, everything appears to be normal.

Upon reopening the project, without making any changes, it became like this directly.

Please help me. If you need any additional information, please let me know, and I’ll respond as soon as possible.

[Hexavx]

This likely because the previous hot-reloaded files aren’t loaded.
Close the project, then delete the Binaries folder on the project folder, then open the project, and let it compile.
Otherwise, you can compile from visual studio.