Add User to Sharepoint Group not working

I have a flow that adds a specified external user to a Sharepoint Group that gives them access to some training resources. I discovered today that the action is not working. When I look at the flow, it shows a successful run. The actions report on Plumsail shows a successful execution. But the external users were not added to the group. I can't find any issue with the flow and nothing else has changed. Any help would be appreciated.

Hello Erik! There is a SharePoint issue that may occur even when the external user is added manually. Each site has a list of all people and all invited persons get there independently of to which group they are added. It causes some SharePoint cache issues so when the person is added to another group and actually has permissions to the site, it says that it is necessary to grant them. To solve the issue, please delete the external user from the list of all people and runt your flow again.

Also, you can do it automatically in the flow. On the required site collection find the current external user through the standard SharePoint connector and delete him from the list using the dynamic output.