Cause

Since a login ID other than for CanvasWorkspace was used to log in to the Artspira app, the ID was changed to that ID for the Artspira app.
 

Solution

If the CanvasWorkspace link setting in the settings screen of the Artspira app is turned on, data from any app can be retrieved, even if the ID displayed on the machine has been changed.
For details, refer to "How to link accounts".