The Upload Document flow runs into this issue only when multiple workspaces are attached to a record.  For example, the Acme account record has four workspaces linked to it (because of the four opportunities related to the Acme account).

The known issue is triggered because platform events auto-combine the execution of the uploaded document into a single execution thread (ideally, the document as we upload from our code is uploaded in the individual thread of execution, so four workspaces means we upload a document to SharePoint in four separate threads. It is important to understand that within Flows, Salesforce carries out its own optimization sequence to improve performance, and thus, it auto-combines the execution of the four document uploads into a single execution. So, the execution runs into a governor limit in the platform, where a platform event cannot be executed after an external API (like uploading a document to SharePoint) is executed.

• The platform Governor Limits simply follows two rules:
  • One platform event execution can trigger multiple external API executions without issues.
  • No platform event can be executed after external API executions.
• When multiple workspaces are linked to an Account, the upload document flow will execute one platform event for each document uploaded. Each platform event execution is supposed to be asynchronous, and the above rules should apply without causing any errors.
  • Due to this underlying bug, all Platform Events are now combined into a single execution (thus, they are not asynchronous).