This one is also great for feedback to have the cron settings be a bit more improved in Celigo.
I’m afraid you now need a small workaround for this case:
In the cron job, select the day of the month and choose 28, 29, 30, and 31.
Then, in the flow itself, use a script to check whether it’s actually the last day of the month, and only proceed if that condition is met.