A new copy/paste feature was added in 2019 Fall update for Dynamics GP to copy/paste in web client GL transaction.
https://community.dynamics.com/gp/b/dynamicsgp/posts/microsoft-dynamics-gp---web-client-excel-copy-and-paste-general-ledger-journal

However this is not compatible with AA, in WEB CLIENT.

AA will be copied in the thick/ RICH client, but not web client features.

Please add the ability to copy in AA data for GL web client