Scheduled function seems to fail silently on first invocation

I am using a scheduled function to have a telegram bot send me a reminder. On it’s very first invocation after deployment, the function seems to fail silently: I am not receiving any reminder, although there is no error message in the function log. From the second invocation on, it seems to work properly.

I have tested and debugged the function locally using the cli without discovering any problems. Any ideas? Is there a way to test if a simple scheduled function w/o any dependencies causes the same problem?

Without a site name or the function URL, we can’t do much.