Thanks for your update with the three fields you are interested in. I have been able to define Custom Field rules that approximate what you see in Admin Columns. If you are not happy with the format or content of the MLA equivalents you can implement a small custom plugin to replicate the Admin Columns results more closely.
This recent support topic is very similar:
Adding parent’s post MetaData
For the first part (create a mapping rule) go through these steps three times:
- Navigate to the Settings/Media Library Assistant “Custom Fields” tab.
- Scroll down to the “Add a new Field and Mapping Rule” area, since you will be adding three new fields.
- In the first text box, enter your field name, “Available Sizes”, “Dimensions” or “File Size”.
- From the Data Source dropdown list, select “size_keys”, “dimensions” or “file_size”. Match the choice here to the name you just entered.
- In the “Existing Text” dropdown list, select “Replace”.
- In the “Format” dropdown list, select “Native” (for Available Sizes), “Native” (for Dimensions) or “Commas” (for File Size).
- Click the “MLA Column” check box to make the field available in the Media/Assistant submenu table. If you want to edit the field manually, check the “Quick Edit” and perhaps the “Bulk Edit” checkbox as well.
- In the “Option:” dropdown list, select “Multi” (for Available Sizes), “Text” (for Dimensions) or “Text” (for File Size).
- Check the “Delete NULL Values” checkbox to save database space for non-image items with no value for your fields.
- Click the “Add Field and Map All Attachments” button to save your new rule and run it to update all of your items. You can also click “Add Field” and then click the “Map All Rules, All Attachments Now” after all three rules are entered and saved.
Do this much and look at the results in the Media/Assistant table.
- The Available Sizes column will look similar to that in Admin Columns, but the links work differently. Admin Columns links to the file for each item-size, while MLA filters the display on that size name.
- The Dimensions column is very similar; MLA does not have spaces separating the parts of the text.
- The MLA File Size column shows the exact byte count, not the “KB” equivalent.
If any of these differences are important, you can go on to the second step, implement a small custom plugin to alter the results. I can give you more specific help with that if you need it.
I will leave this topic unresolved until I hear back from you with the results of the above suggestions.