Latest version of the compiler introduced a bug making you unable to introduce your own custom events. You can still have custom functions, this is specifically impacting only functions who's name start with an underscore. This was possible in older versions, but broke a couple of days ago. Not being able to define custom events prevents the UdonPie script from being called by another Udon graph.
Edit: This seems to be related to commit 914f9d9617bdcda149d03e73e806ae46d7af709b
Problem
Latest version of the compiler introduced a bug making you unable to introduce your own custom events. You can still have custom functions, this is specifically impacting only functions who's name start with an underscore. This was possible in older versions, but broke a couple of days ago. Not being able to define custom events prevents the UdonPie script from being called by another Udon graph.
Edit: This seems to be related to commit 914f9d9617bdcda149d03e73e806ae46d7af709b
Example
Running this through the compiler simply prints "_custom" and then exits. It does not produce any Uasm.