Hi David,
You did not mention if you edited RAW files or JPG files. In the case of using JPGs, you will likely get a more successful alignment without any edits. Editing JPGs can result in pixels that are too different in consecutive images that RC rejects them as viable tie-points.
You can also change the alignment setting for the ‘Image overlap’. If you set this value to ‘Low’ then RC will use a larger portion of each image to find matching tie-points. Increasing this from low to medium or high can decrease processing time if your overlap is good but it can mean that some oblique images fail to match.
You can also try grouping all the images together so that they share the same camera calibration. You can do this by clicking on ‘Images’ in the left sidebar. A new menu will pop-up with white buttons, click on ‘Group’.