Create Planner Task action stiopped working after 28th October update

[MrNigel]

FOR INFO ONLY

A recent MS update to Flow back-end has 'broken' the Planner Create Task action.  We have three Flows that all went in to 'fail' state after 28th October.  

The error is "

message": "The request is invalid:\r\nInvalid JSON. The property name '' is not valid. The name of a property cannot be empty.",

I have an active ticket with the Flow engineering team and will update this post when the solution is available.

[MrNigel · Accepted solution]

SOLVED:  We have multiple assignees added to the task via individual variables containing the email ids.  These are automatically semi-colon separated when you insert them INCLUDING a trailing semi-colon after the last variable.

IF you delete that last semi-colon it works as it did prior to 29th October.