I've been trying to get a simple Planner board (with a bunch of buckets) with a bunch of tasks (and multiple assignees) into a SharePoint list (single row for each task). I've been following Tom Riha's approach here:
https://tomriha.com/export-planner-assigned-users-into-excel-with-power-automate/
I've been getting stuck at in this Set Variable step:

When running, the error produced is:
The variable 'var_mappingTable' of type 'Object' cannot be initialized or updated with value of type 'String'. The variable 'var_mappingTable' only supports values of types 'Object'.
In the comments of the blog article, someone else had the issue, to which Tom responded that the wrong brackets are being used.
The brackets being used at {"":""} as shown at the top here, also per the article. Everything else appears to run correctly.

Any support would be appreciated.