Using GAMADV, I'm receiving this error when attempting to move calendar events:
Move Failed: You need to have writer access to both calendars.
After running the below commands, I have confirmed the account I'm using for GAM has writer access to both calendars.
gam calendar <user_email1> showacl
gam calendar <user_email2> showacl
I ran into the same error attempting to move a different event on a different calendar yesterday, as well. When installing GAMADV, I made sure to include all scopes. Any suggestions?