After migration from 5 to 6, I also had to change menu link to new AcyMailing 6 ยป Newsletters archive. But the old newsletters have missing content. It just displays tags like:
{joomlacontent:293| type:intro| link| pict:1| format:TOP_LEFT}
Also the URL from images are not pointing to original location, but now to ..../media/com_acymailing/upload/....
Any solution for this?