I have a script in my sandbox that syncs some custom records to the itemvendor list on items. If I use

record.load

and

Record.save()

, it does not kick off the script that should sync the custom record to the corresponding itemvendor line, but if I edit and save the same record in the UI it does. The deployment for that script does have User Event Script enabled in the Execution Context. I'm doing load and save from a UE script.

User Events don't trigger other User Events

You can use a task or other intermediate script type to get around this limitation @reptar

unless you really need this to be immediate it should be a batch action - mr script. if it needs to be immediate then using e.g. a suitelet as a mediator is a viable solution.