User data function invocation failed (but works in testing)

After a long stint working with microsoft tech support (big thanks to Naeem), we finally found the source of the issue:

I had, not knowing better, used the line 

udf = fn.UserDataFunctions()

at the beginning of every (publicly visible) function in the document, like this:

udf = fn.UserDataFunctions()

@udf.connection(argName="sqlDB", alias="COGSdb")
@udf.function()

async def runAllCogsCalculations(sqlDB: fn.FabricSqlConnection) -> str:

While for some reason this does not cause issues in testing, it leads to all functions defined before the last instance of the line to be unavailable when published, without producing a clear error as to why.

Luckily, the solution is very simple: just remove all but the first use of "udf = fn.UserDataFunctions()" without changing anything else, and the issue should be resolved. 

Hopefully this helps someone who's facing the same issue. I also made sure to report the problem somehow bypassing testing to microsoft, and I hope in the future there will be a proper error to prevent this.