The bug

As of 23w41a, the command

/execute store success ... run function <FUNCTION NAME>

doesn't store anything if the function doesn't run the /return command.

This is intended when storing the result, but probably not when storing the success. Prior to 23w41a, the success was stored as 1 if the function was run, and 0 if the function couldn't be found.

How to reproduce

1. Create any function that does not contain the /return command
2. Create an objective displayed in the sidebar:

   /scoreboard objectives add test dummy

   /scoreboard objectives setdisplay sidebar test

3. Run the function, storing the success in the scoreboard objective:

   /execute store success score test test run function <FUNCTION NAME>

   → Nothing appears in the sidebar