Hi @Yudistara,
Could you please show more details about the issue within your flow?
Further, could you please show a bit more about the error message?
I think there is something issue with your Stay Calendar Flow, the "Create event (V2)" action would create Outlook events within your Outlook calendar based on the amount of the Attendees of the new created SharePoint calendar event. In other words, if there are 4 attendees within your new created SharePoint calendar event, the "Create event (V2)" action would create 4 events within your Outlook calendar.
I have made a test on my side and please take a try with the following workaround:
Stay Calendar Flow:
- Add a "When an item is created" trigger, specify Site Address and List Name set to your Event list.
- Add a Variables->"Initialize variable" action, Name set to Attendees, Type set to String and Value set to empty.
- Add a "Apply to each" action, input parameter set to Attendees dynamic content of the trigger. Within "Apply to each" action, add a Compose action, Inputs field set to following formula:
concat(item()?['Email'],';',variables('Attendees'))
Add a "Set variable" action, Name set to Attendees, Value set to output of the "Compose" action.
- Under "Apply to each" action, add a "Create event (V2)" action, specify Calendar id, Required attendees field set to Attendees variable, type ID dynamic content of the trigger within the Body field of the "Create event (V2)" action, Is HTML field set to Yes.
Image reference:

The flow works successfully as below:


Update Calendar Flow:

Within Condition box of the "Filter array" action, click "Edit in advanced mode", type the following formula:
@and(contains(item()?['Body'], string(triggerBody()?['ID'])),contains(item()?['Body'], triggerBody()?['Description']))
Best regards,
Kris